Why are they called droppers, when one of the most common uses is as a type of Item Elevator? Why not simply allow upside-down hoppers (which do not suck items, only send items upward), as non-logical as that seem to be. But then, when is minecraft completely logical.
Dropper towers are something that people are using as a means of creating a item elevator ever since you could face a dropper upward, and glass item elevators became so glitchy. (Update: see the piston-less glass item elevator by "test137E29", link at end of post)
But droppers are not really designed for 'piping' items (though in the first few snapshots of v1.5 they were), and as such there are problems when used in this way.
That said this was written for Minecraft v1.5.2 to v1.7, in case things change, though I am updating this document as new facts, techniques and designs come to light.
After studying many dropper towers, building many on various servers, multi-player and single-player, I came up with these notes, showing just how complex dropper towers can be to get working correctly, what designs actually do work, and what did not. But more imprtantally why designs fail.
NOTE: You can see many of the designs on my CubeKrowd Creative Plot. This world is open to everyone, and anyone is allowed to get a creative plot for there own experiments and or 'member application builds'. To see these designs, minecraft login to "cubekrowd.net" go to the 'creative plot' world ("/cr" from lobby), and jump to my creative plot ("/plotme home antofthy"). I lost many of the early builds in a major plot reset some time ago, but have been rebuilding most designs on my plot since that time.
Comparator Clocked Droppers (not towers)
The following shows a number of methods of using a comparators to clock a dropper, (not a dropper tower)
The purpose of these circuit screen-shots is not to show what is 'good' or 'bad' but to show just how much variation is possible. Basically there is a lot of ways you can arrange the comparator circuits.
Most of these circuits work well for single droppers, or even dispensers, but generally do not work (as explained later) when used for dropper towers. This is where most people have problems in designing and building their own tower.
Warning: If a block is used between the dropper and comparator that block should not become powered. Doing so may result in a comparator lockup or other undesirable feedback loop. However I and many others have powered this separation block in some designs clocks without problems. Caution is recommended.
Powering a Dropper Tower
(This is a must read if you really want to understand and fix dropper towers)
In the previous section we saw that there are many methods of powering droppers, but what effects do these have on a tower of droppers.
So here is what I learned from many experiments different ways of powering a dropper tower. I did not look at a sequence of sideways or downward facing droppers, as these are better handled by hopper pipes.
Note that exactly when dropper is powered does not always make a lot of sense, and some of these may be 'fixed' in later updates. Then again, they my not be fixed.
But unlike most other powered devices, it is not just what is powered that matters, but the exact order in which they are powered by the signal, as well as Quasi-connectivity powering effects.
Powering an dropper without items 'clicks'.
A dropper ejecting an item into the air (or water) 'clicks' (differently)
Redstone wire running next to (not into) a dropper (on half slab),
does not power any dropper (standard redstone mechanics)
Redstone torch next to a block (to power that block) next to the dropper
tower, does nothing. The block next to tower is only weakly powered, so no
power is transmitted on to dropper.
Redstone wire on a solid block running next to (not into) a dropper,
OR a repeater OR wire directly feeding into a solid block next to a dropper,
OR a redstone dot on a block next to a block next to the dropper tower,
powers only dropper next to the solid block. (weakly powered dropper).
This is the ONLY methods that will activate single dropper!
But.... Due to Quasi-connectivity effects, the dropper below may also become powered due to some type of update effect, and then remain powered until updated again after the power is removed.
This becomes a major problem in Fully-Tested Dropper Towers (see below). It can also become a problem when stacking towers (which is essentually what fully-tested towers are.
This method is not recommended, except in Fully Tested designs, where you really have no choice about it. It is just another reason that quasi-connectivity is simply a BAD IDEA.
On the other hand, purpledragonnuke published a dropper tower, as part of a larger storage silo video which makes use of the quasi-connectivity to produce a Stacked Tower design (every two layers).
Redstone torch next to a dropper (no block above the torch)
Powers 2 droppers the one next to torch, and one below. But
the dropper above is not powered! Only 2 droppers are powered!
Now while a tower of lamps (see image), will only show one lamp powered, 2 droppers are powered! The lower dropper will receive power first, meaning the item in that dropper will get moved up BEFORE the dropper next to the torch moves its item. That means if there is only one item in the lower dropper, and none in the one next to the torch, that item move up 2 droppers, to the unpowered dropper above the torch.
In other words if a single item is anywhere in these two droppers, it will always ends up in the next dropper in sequence. This makes this powering method the only one that only powers two droppers. Also if extra pusle is recieved the droppers will be cleared of any 'extra' item that make have become stuck. This is important in some stacked and over-clocked designs.
Note that the lower dropper is actually being powered by quasi-connectivity, but is also being updated immediately, and as such does not become activated due to uncontrolled through BUD effects.
Wire feeding into a dropper (on a half slab),
OR a repeater directly feeding a dropper,
powers 3 droppers, (one above and below)
The middle dropper (being feed directly will be powered first, then the other two droppers above and below. As such only an item in middle dropper can jump two droppers. Any item in the lower dropper will only move up one to the middle 'directly powered' dropper.
Warning quasi-connectivity effect may actually cause the dropper two below from also being powered if a it recieves a redstone update.
Redstone torch next to tower, under a solid block (also next to tower),
OR a wire feeding into a dropper on a solid block,
will also power 3 droppers, but in a different order to the previous one!
The lower and upper droppers will be powered first, followed by the one in the middle next to the wire or torch. Only the item in the lower dropper can jump two droppers on a single power pulse.
Note that the order is different between a wire feed on a solid block vs a wire feed on a half-slab!
Tower of Redstone blocks next to the droppers, pushed by a piston upward,
causes instant transport of an item through all droppers!
This is a technique known as a 0-tick pulse, and is caused by the redstone blocks being pushed by the pistons to become a entity. While the redstone block is an entity, it can not power the droppers, and as such droppers become momentarily unpowered. When power is restored it is restored from bottom upward within the same tick, thuch transporting an item all the way up to the top all within the same tick.
I have yet to see a full design based on this technique. Probably as it is noisy, and limited to the 12 block push limit of pistons.
Ideally when powering droppers you do not want to hear any extra 'clicks' during a full item run, as it means a dropper somewhere is getting powered (if not already powered) without items. Though you may do this on purpose at the start or end of a item run (see below).
Note that it is '3 dropper powering' methods that generally cause problems in most tower designs. That is because you either need 2 ticks to move an item through the 3 droppers (with extra clicks), OR you end up with overlapping powering of the droppers, which can cause timing problems and power interferance patterns, especialy when trying to stack towers. These problems are discussed in more detail below.
Because of this almost all perfectly silent dropper towers, especially at the start and end of a run, use the redstone torch 2 dropper powering methods, even though redstone towers burn out if driven faster than a 3 tick cycle.
UPDATE: Recent confirmation from ZipKrowd members: Kavo, and Panda has shown that redstone torches (and many other redstone input devices) are being effected by random ticks, causing the normal torch update delay to be short circuited at random! This is disastrous for dropper towers that rely on some type of redstone torch tower, as the timings might go wrong every now and then.
The result, as as been seen on some long running towers on multi-player server, is that items will be occasionally left in a dropper. This is not critical for a "Dropper Hose Pipe Design " as these tend to automatically self-clear, a random item, but for a silent "Pulsed Item Wave Design" this is very bad news as it will every so often leave an item in one of the droppers until manually cleared.
No clock lockups
First, if a comparator does not run a clock of some kind, then two items in the dropper being tested will cause the comparator test to 'lockup'. For example, in GenerickB's dropper tower, without a item feed limiter it will fail. I will not say much more on this as the cause of this problem is obvious, and not really a 'stuck item', just a lack multi-item handling using a clock of some kind.
As such some type of clocking loop is typically essential in a reliable design, though there are designs that don't need it.
The Classic Problem Dropper Tower
This is design that has been re-discovered by many people even without realizing that it has already published, many, many times before. Who discovered it first does not matter as they are such an 'obvious' design.
Yes they work, but will fail in random spaced input and multi-level feeds.
Basically you take a standard 'clocked dropper' method (see above) and use it to power the droppers using a direct wire feed or repeater. Both of which will typically move an item up two levels to the next 'comparator clock'.
Again these work, but they are not reliable!
Power Interaction
The real problem is that power interactions can cause an item to end up in unexpected dropper. One that does not have a comparator to detect them. When this happens an item will remain in that dropper, though the actual item itself may be replaced by other items passing through the tower.
This generally happens around the point where two comparator tested 'mini-towers' (typically only 2 high) are stacked (see typical examples above).
When power interactions extend beyond the individual stacked mini-tower. The stacked tower can clock at a different rate to the tower below it, especially when items are delivered with irregular pauses, or more items get feed in at the higher level. It may even be caused by players leaving and entering chunks, or moving up and down a very tall tower.
The rate at which an item gets stuck in many cases may only be one item per stack, or it can in very bad cases be half the items in a stack. It does not matter if the items are all the same type sort, many different sorts, or even non-stacking item. For example I threw 3 double chests of bows (collected from mob drops) through one tower design, and had 3 bows get 'stuck', in the upper sections of the tower.
Note that once an item is stuck in a tower, it does not mean it remains in that specific dropper. Other small pauses in the item feed, and/or timing disruptions can cause a stuck item to move and drift slowly upward, especially in high volume towers. These types of towers will typically 'self-clear' stuck items over time, hopefully at a rate faster in which items get stuck.
These timing issues can be very common in a item feed from a mob system, or in towers where users throw many different items into a hopper feed at higher levels, while items are coming up from below. Basically the towers typically fail in a practical working base of operations, but work prefectly in ordered tests such as in a creative world.
The stuck item rate is rare enough that the towers will typically pass the testing phase, and only start failing when placed in a more practical situation. As a result, designers often think they find a simple reliable design, and immediately publish it, without further testing in a more practical environment.
If it is discovered, designer will typically give up on stacked designs, and work more on a simpler single clock, base feed only design, that most of the reliable designs follow. But these are not always the most useful, typically being noisy or have no mid-level item feed points.
Addendum...
There was one other problem I saw that was a cause for concern. It may however have been been a purely random glitch on a SMP server on whcih I was trialing the dropper tower.
I saw a single item that was 'flip-flopping' between the repeater powered dropper, and the dropper two above. The dropper with comparator was being directly powered by a repeater.
Opening the dropper showed that one item (gunpowder) appearing, disappearing and re-appearing again as it jumped back and forth between these two droppers, with the comparator clock constantly attempting to send that item further but failing to do so for no apparent reason. That is the item moved but was constantly restored back to where it was, causing the comparator to try again.
When another item was put in, the problem fixed itself without becoming stuck. This only happened once and I don't use that design any more (due to power interaction issues when stacking).
Stacking Towers Vertically
Most of the designs that have been published only lets you feed items at the bottom of the tower, where a single comparator runs the tower. That is understandable as these designs are resource light and often have few 'power interaction' issues to cause items to become stuck.
But you often want to add a feed into the middle of a tower. One way is to have an expensive hopper pipe, just going down to the bottom, simply to feed items back into the tower, so they go to the very top. But that is often thought of as being nonsensical. Though this does work and is a very clean solution.!
As a result you generally want to make two separate dropper towers, and stack them on top of each other. Or putting it in another way, you want to break your dropper tower into two separate comparator checked and clocked towers, that is stacked on top of each other. New items can then be feed into the middle of the tower, at the base of the stacked dropper tower.
Alternatively you may want to break a tower into two or more sections simply to reduce 'over-clocking' requirements (see below) and thus reduce excessive clicking at the start and/or end of an item feed.
But as soon as you break a tower into two, you run the risk of the stuck item issue, due to power interaction problems. That is by breaking the tower into two, many working designs will suddenly cause items to become stuck, either in the dropper one below the comparator, or somewhere just above that comparator.
Designs that rely on a steady item feed (no comparator driven clock) will also break as an extra item feed can now over feed such towers, causing even more problems.
One simple solution to this problem, and most other stuck item problems, is to completely isolate the mini-towers. To do this replace the destination dropper with a hopper and pipe the items to a completely separate dropper tower, perhaps just one block further over. That is each stacked tower is displaced horizontally by at least a single block using a isolation hopper).
For example this image posted to the forums, show multiple 2-dropper 'towers' which are staggered using hoppers to isolate the dropper powering arrangement that was used.
If you also add a buffering double chest, then the new tower will start one block lower (hoppers can only suck items from a chest above them, so the hopper feed into the next tower will be one block lower).
These solutions work great, but a zig-zaging series of towers can look messy
in what would otherwise be a single long tower of stacked droppers. But in
some situations, this is recommended because of the extra buffering the
isolating hoppers (and chests) can provide (see "Item Jams" below).
Note that using isolation hoppers is also more resource intensive due to the extra iron needed for isolation hoppers.
Be warned that, power effects can also extend to the hopper that the final dropper may be feeding. That is while the final dropper is receiving power the hopper above it may also receive power and thus will not pass items on to the next hopper (or chest).
This is typically not regarded as a major problem as long as the tower powering method does not leave the tower in a powered state by default. But as slowing the item transport away from a dropper tower can cause item jams (see below) it can be just as important to ensure the power does not extending beyond the top of the tower, not just at the bottom of a tower.
The better solution is to ensure that you never have an overlap in dropper powering between the two stacked mini-towers. That is what the previous power feed guide is for. In this way dropper towers can be stacked without needing isolating hoppers or item buffers.
A typical way of doing this is to have a final redstone torch in a tower does not have a final block above it. That is ensure to power 2 and only 2 droppers at the top of the lower tower (item moves up 2 droppers on one pulse).
For example a typical single torch tower "Pulsed Item Design" (see below), only needs to NOT have a block placed above a torch, to prevent power overlaps. I do this on purpose in my own Stacked Tower Design.
But remember you cannot place a comparator immediately above that redstone torch. Also you cannot move the comparator one block away from the dropper as a comparator needs a solid intervening block, and it is this block you wanted to remove. As such when stacking the second you must either have the redstone torches on a different side to the comparitor, or rotate the clocking circuit 90 degrees for each tower stack.
One 3 dropper powering example which solves this power interaction problem is by timeofsouls (see Stacked Tower Designs below). This is designed so that the clock generates one extra pulse on the the last item (due to an longer repeater delay). This ensures all items in each mini-stack of three droppers are sent up to the next tower. Of course it does cause clicking as each mini-tower clears. But that extra pulse will also clear any stuck item that may appear in the tower (see next section).
Tower Stacking and Item Jams
There is another way items can become stuck and leave a large number of items in a untested dropper, and this does not involve any type of power interaction problem.
If the container block the top most dropper is feeding items into (which may be the dropper of a mini-tower that is stacked on top of it) does not have a slot the item can go into. When this happens the item simply does not move and so becomes 'stuck', in that top most dropper, which is typically not comparitor tested.
The fact that droppers randomly pick items (and rightly so) could mean that one time an item can be pushed, but another time it can't, which introduces randomness into the system. Hoppers Piplines can also mix up items when a different item is suddenly recieved in its first slot, and that also randomize and shuffle item types that is entering the dropper tower.
The problem is made worse by the fact that droppers and hoppers always stick items the first available free slot, even if there is a incomplete stack of the same item somewhere else in the container. That is they can generate multiple partly full slots with the same item, and thus preventing that slot from being available to some other items, even though it could (with some inventory management) accept that item.
Many times I have looked in a jammed hopper pipe to see all 5 slots containing a small number of the same item. That is the hopper was not actually full, just has no slot available for some other type of item, and thus preventing any feeding hopper/dropper pushing in some other item.
Note this 'put in first possible slot problem' does not happen when users 'shift-click' items into such containers, only when a hopper or dropper feed items into containers. I consider this to be a bug.
This is a buffering problem. Basically the destination container, be it hopper, dropper, chest, or their minecart variants, is not able to accept the item being 'pushed' into it.
In stacked towers this is typically not an issue, as you are feeding items to it at the same rate that the tower above is handling them. It however can become a problem if that upper mini-tower is also receiving a lot of varied items from another source. For example from a dump of a players inventory, or a large storage chest of adhoc items, or even a second mob system.
The situation becomes worse when the tower is pushing items into a hopper, which only has 5 slots, and so while the dropper can select from 9 different items, the hopper and only recieve 5 different types.
A double chest however has a lot of slots, and so provides a ideal buffer for situations whenever too many varied items are involved.
One other solution to this buffering problem is to add one extra comparator test and clock to just the top most dropper of the lower tower. This was presented as part of a item sorter in
IronStoneMine Compact Automated Item Sorting
This is not I believe a ideal solution as it only provides a small buffer (the top most dropper) to items not able to complete their journey. IronStoneMine's dropper tower however was also only 3 droppers high, non-stacking, and not dealing with too many different types of items in his design. As such I doubt that his 'dropper buffer' would also become full.
Over-clocking the tower can also be a solution. Even if one run of items does not fully clear the item jam during the over-clocked period, successive later runs will slowly clear those stuck items. For this reason a small amount of over-clocking, even in tower designs that normally do not need it, may be a good idea. If you don't mind a small amount of extra clicking at the end of an item run.
A "fully comparator tested tower" which uses a comparator test and also clocks on every dropper, will also never experience a item jam. If an item jam develops, the tower will continue to try moving the items until the cause of the problem is cleared up the line.
Fully Comparator Tested Tower
This is the first 'obvious' design to tower builders and one that is also typically rejected very quickly (perhaps too quickly) due to circuit packing problems.
Basically you use a comparator to test each and every dropper in the tower and then power the dropper if it has any items.
You will never 'lose' items. As at no point can an item exist in a dropper that is not tested. It also does not matter if multiple droppers get powered, as skipping droppers, or pulling items from below cannot result in stuck items. It does not matter where the item ends up as all droppers are tested.
However stacking the circuits at every level is a very difficult problem. First you can only place a comparator, repeater, or even redstone wire on a supporting block that will use up space in the circuit below. Secondly any raw redstone wire supported by a solid block (though not a half slab) will power that block, which can in turn can power the circuit below.
Because of these 'support' and 'packing' problems you cannot simply stack two identical circuits on top of each other. And so you will need at least two different circuits (perhaps the same circuit simply rotated 90 degrees) from one level to the next level. This will make the resulting redstone very heavy and dense, limiting access and perhaps even wrapping completely around the tower on three or even all four sides.
If each each circuit is not clocked (as in GenerickB's design) you must restrict the item feed to one at a time, as a comparator may become locked up by 2 items, with one getting sent on, while the other keeps the comparator powered, preventing further action.
A major problem with fully tested dropper towers is the smooth flow of items through the tower. If the clocking repeater is set to 1 tick delay, the items in the tower start arriving in spurts with significant pauses between. That is the items arrive in a irregular way, in the form of a interference pattern. That inturn reduces the overall speed in delivering a stack of items, by around 50%. All the items will still arrive, as you cannot lose items in a fully-tested dropper tower, just not as quickly as expected.
The problem seems to be caused by the dreaded quasi-connectivity problem that not only plaques pistons, but also dispensers and in our case droppers. That means the clock not only powers the current dropper, it also powers (with redstone updates) the dropper below the current one, effectively clocking two droppers, when only one dropper should have been powered.
Note that this does not cause items to be stuck, as that is imposible in a fully-tested tower, but it does cause severe miss-timings between each dropper clocked layer, that in turn causes delays in comparators detecting and clocking items through the tower. So far only one specific clocking method has been found which has a timing that prevents this problem. See "Fish Bone Fully Tested Dropper Tower" below, though it is likely to break due to update timing changes in 1.8.
The simplest solution to prevent this problem is to use at least a 2 tick delay in the comparator clocks, which causes a smooth flow of items through the tower, and is a lot faster than if you had used 1 tick repeater delays in most fully-tested tower designs. As mentioned the exception is the "Fishbone Tower" below.
Advantages
* PERFECTLY SILENT - If you only power one dropper!
* Items can be feed in at ANY point in the dropper tower (if clocked)
* Stuck Items are not possible, as they will be found and handled.
* Item Jams (due to the destination being 'full') will clear automatically Disadvantages
* RESOURCE INTENSIVE - very dense redstone use at every level
* Very large foot print on every level in the tower.
* Redstone has to 'interleave' to allow a comparator check on all droppers
* So much redstone can make it hard to add mid-level hopper feeds.
* Quasi-Connectivity interference effects can slow item rate by 50%.
Example Tower Designs...
GenerikB Minecraft Item Elevator Tutorial (and challenge)
A highly compact interleaving of the testing circuit, while only powering one dropper at a time. There are no clocks, so if a dropper some how ends up with two items it will become locked in a permanent on state.
To prevent lockups a special redstone 'dot' is added next to the input hooper to slow the feed to only one item at a time. Limiting item flow also spaces the items in the tower, and prevents BUD, or other timing interference pattern effects.
This means you can not add a extra mid-level item feed. And it becomes especially prone to an item jam, which will permanently shut down the tower. Bud effects from block updates next to a running dropper tower can also have a devastating effect.
The moral of this example is that comparators not only need to test the droppers, but they must also should clock the droppers when multiple items are present.
CubeHamster Silent Dropavator
Every dropper is comparator tested and clocked dropper tower, but the circuits wraps completely around the dropper tower. This would make make any sort of mid-level item feed a practical impossibility, unless you stagger the towers with hopper pipes. Some special circuit modifications is even needed to simply allow you to add the input hopper pipe.
Basically as comparators can not 'stack' you must place comparators on two different alternating sides of the dropper tower, to avoid problems. There are many variants, just as there is many dropper clocking methods.
The two designs are ones I came up with but both are obvious, I would not really put my name to them. Though there are as many variants as there are dropper clocks. Interaction effects means the clocking repeater must be set at 2-ticks, to prevent an irregular flow of items (see discussion above).
Timing tests using a 16 high tower timing the delivery of a hopper feed stack of 64 items, with top most dropper feeding a chest at the very top of the tower. 1 tick delay on repeater: 75 seconds. 2 tick delay on repeater: 48 seconds. (See post 34 of this topic)
Alternating Side-to-side Comparator Tested, using Fast but Seperate Clocks
(the tower) (the clock, extra delay on first repeater)
This uses the output of the testing comparator to run a seperate fast comparitor clock. It is one of the standard types of dropper clocks, which is typically used run a dropper a higher speed than then normal comparator-repeater clocks. Typically fast enough to allow the dropper to handle items from two hopper pipelines feeding it. Though of course a single destination hopper pipeline would not be able to accept such high rate of item flow.
Unfortunately this clock is also known to generate extra click when the last item in the dropper has been sent. That extra click is caused by delays in the circuit and the very high speed of the separate clock. As a a single hopper pipeline can not feed such a dropper tower fast enough, that 'empty' state would be reached quite regularly. As a result thsi tower clicks fairly randomly while also causing item delivery to be in spurts of roughly 4 items at a time.
Even with the irregular delivery, this tower is much faster that previous ones. Timing tests show that it can deliver a hopper feed stack of 64 itmes to the a chest at the top of a 16 high tower in a average of 35 seconds (Using the tower pictured).
As the input is slowed by the single hopper feed, placing a stack of items directly in the lowest hopper, delivered those items to the top chest in just 23 seconds, though arrival was still fairly irregular, and it still clicks at the end, though not in the middle of the run. That means placing a second hopper feed below the testing comparator for the second dropper would be a practical improvement.
Actually this design is pretty close to TimeOfSouls Max Speed Dropper Tower. The only difference is that his design is a Stacked Mini-Tower Design, that uses the fast comparitor clock to run 3 droppers at a time instead of just one, and all the clocks are on one side. The redstone is also more open allowing you to feed two hopper pipes from a double chest, more easilly. As such I refer you to his design for the next stage in the development for a high speed tower design.
A variation I came up with that manages to place all the comparators all on the same side of the droppers, allowing the circuit to shift to the left and right. This make smaller more compact fully tested and clocked tower, using a smaller 6x3 footprint.
The final image shows an alternative for one circuit, making the tower fit in a 5x4 footprint, though the front remains only 3 wide.
Interaction effects will slow the towers item rate to irregular spurts unless you set all repeaters to use a 2 tick delay (see above). Both variants of the tower delivered a stack of 64 items up 16 droppers in 47 seconds. not the fastest, but not slow either.
Fishbone Tower: Fully Tested, Interference Free, Fast and Silent Tower
(the tower) (half slab needed next to hopper inputs)
With the help of M0RT1F3RU5 on this forums, a clock was found that has a 1 tick comparator testing clock but which does not cause interferance between each layer of the dropper clocks. This means a tower clocked using this specific dropper clocking method does not have a slow irregular arrival of items at the top.
Time to deliver 1 stack of 64 items from a hopper feed to a chest 16 block up, 34 seconds. A fast, reliable and above all silent, fully-tested tower.
The name is derived from the fish skeleton look of the tower, especially if you use half slabs for the blocks holding the redstone circuity, instead of full blocks. For more information see post 42 of this topic)
You must use this exact clocking setup without change to get a interference free, and smooth fast delivery of items in a fully-tested tower, as small seemingly inconsequential change can cause the interferance pattern to return. For example, replacing the repeater that powers the block powering the droppers with a slightly faster comparator will cause the interferance to to return.
However replacing the solid block the clocking repeater feeds with redstone dust, does not cause a problem, and doing so will make the tower look even more 'fishbone' like.
WARNING: The speed is fragile, the timing interferance is likely to return in MC v1.8
FarhanTZ's Dropper Tower
Another fully tested tower, using the standard 2 wide clock of most of the designs, but twisting 90 degrees each time. Droppers completely accessible on one side, but its large foot print makes it difficult to build into a larger design.
After failing to find a good "Fully Tested Tower Design", the next method is to simply cycle the tower using a single comparator at the base, and then power all the droppers from that comparator, (or clock). The result is a design that I call a 'hosepipe' design.
The tower is only power cycled once, and only once, for each new item in the detected dropper. But items will always be left permanently in tower. What many people don't realize however is that these items are NOT stuck.
The items will continue to move up the tower, as more items arrive at the base. In other words the items that are left in the tower are just waiting for more items to push them further upward. This is much like water in a garden hose. When you turn on a tap, water will immediately come out, but it is not the same water that just entered the hose.
Is that a bad thing? No. If attached to a mob system, the tower will constantly be flushed by new items, especially useless zombie flesh!
The key reason these towers work as they do is that the dropper powering will pulse up the tower much faster that the items themselves move up the tower. That is either a half-slab (or glowstone) power riser is used (instant power), or a single block torch tower is used (two droppers per tick). Either way items only move up a certain distance (typically 2 or 4 droppers) each time the tower is 'pulsed', though the initial number of droppers up to the first 'in-the-pipe' item can be more than this.
A secondary 'flush' clock can added either by having the first comparitor power a clock of some kind. Alternativally by setting the testing comparator to difference mode (light the output torch) and adding a switch on the bottom dropper, or the intervening block. That turns the testing comparator into a 'clock'. Typically it is not needed, unless the player is leaving a site, and really wants all the items 'delivered'. See Over-Clocked Tower Designs below.
Advantages
* Very resource light
* No clicking, except during initial loading of in-pipe items.
* simple design using the right power feeds.
* a small over-clock and/or flush system can be added to clear tower. Disadvantages
* Always has one item every few droppers in the tower 'in-the-pipe'.
* Can be hard to get that 'special item' out of the tower, unless flushed.
Example Tower Designs...
Simple Hose Pipe Dropper Tower
Very simple circuit, and silent. Just directly power a half-slab redstone riser next to dropper tower from the item detection comparator loop. It fires once every 2 ticks (no delay on 1 tick repeater) for each item in detected dropper, causing items to move up the tower two droppers, about as fast as a single hopper feed.
It does click while items are initially loaded into tower, but then it becomes Perfectly Silent. Continuing the signal higher than 15 blocks becomes problematical, and linkage between stacks of towers may require hoppers to isolate the towers.
This is actually similar to sZPeddy's Item Elevator (see below), but without any over-clocking circuit (I found his design later).
This design is basically a dropper tower with a single block torch tower running up next to it, directly hooked into the comparator clock. No extra clocking is provided, (such as is ACtennisAC tower, below), so items will be left in the dropper tower. But again these are not actually stuck, just waiting.
For this specific varient, the first item is left in the 6th dropper, and then as with all torch tower hose-pipe designs, every 4 droppers after that.
This has to be the smallest, simplest dropper tower you can possibly make. As long as you don't mind a couple of extra clicks at start and end of an item feed, it is actually silent in the middle of an item run.
The torch tower must run on a 3 tick clock cycle (2 on the repeater), it can run faster on a 2 tick cycle, but the torches may burn out occasionally leaving an occasional stuck item, typically in the second dropper from teh bottom.
The design can also be over-clocked (see that section) which helps clear any posible stuck items, and if clocked a lot, clear the 'in-pipe' items, at the end of a run.
For an extra mid-level item feed you can simply break the tower, and add another comparator circuit, so as to 'stack' the tower. The next comparator and feed point must be in the dropper above the final torch in the lower tower. The block above that torch must also be removed, to prevent overlapped dropper powering, and interfering with each other (see images).
As always there are lots of variations in design, but it is so common no-one can really claim ownership, except for a specific variation.
You should also see "AntOfThy's Stacked Tower" variation (below), which while using this type of hose-pipe design, does not leave items in the tower!
Tilable Hose Pipe Dropper Tower
A tilable version of the Hose Pipe Dropper Tower, using a hopper clock (1 item) to drive the tower. The 'in-pipe' items start at the 5th dropper and every 4th dropper after that, and once in place the tower becomes perfectly silent.
This is a highly recommended tower, especially as it is the only tilable dropper tower known. This make it well suited for connection to a bank of item sorters as part of a compact storage system.
However you cannot simply stack the tower (see conditions in the previous tower design) for a mid-level item feed, as the torch tower being 'in-line' with the comparitor will interfer causing power interferance issues and probably timing issues as well. That can be solved only by destroying the 'tilable' feature of the design.
Drakkart's Droppervator Tutorial
This was posted about 20 days after 'host-pipe' descriptions was first published on the MineCraft forums. And to me it shows that the message about 'hose-pipe designs' is getting through. It is a slightly simpler variation, leaving the first item in the 5th dropper (4 droppers up from the comparator tested dropper), and then every 4th dropper from there on.
However the design powers the block that sits between the first dropper and the testing comparator (bottom block for the redstone torch tower). This as mentioned before is not a good idea simply as the comparator can then become powered not from the dropper contents, but from the powered block.
Strangely this does not seem to happen in this case, though I have seen it happen in other designs where that block becomes powered. Why this is case here I am not certain, and to me it is a part of some of the mysterious behaviour I have seen in many redstone designs.
Over-Clocked Tower, after the last item
Rather that leaving items in the tower (as in the "Hose-pipe Design"), the tower is over-clocked after the last item leaves the bottom most dropper, until all the droppers are clear of items.
This generally requires some form of extended clocking circuits at the tower base, with the tower power coming from a separate clock to that of the testing comparator.
This over-clocking period tends to produce a lot (and I mean a lot) of extra clicking, especially at the end of a item run. This noise can be very annoying for dropper towers. Especially if they are in your main base.
By using a 'half-slab' power feed with this method you can clock the tower at a very high speed, allowing you to transport items at a maximum possible rate, without redstone torch limitations. As such these tower include 'maximum speed' type dropper towers.
There is also a method of clocking a torch tower at high speed by pistoning a redstone block above a single redstone wire, which results in a phase shift of the pulses and bypassing the games torch burn out code. But I would not rely on it.
Advantages
* Resource light
* larger circuit for clock and detection pulse sustaining
* Can be made to flow items at double the rate of a hoppers Disadvantages
* Generally LOTS CLICKING from powering empty hoppers (esp. at end)
* may need pistons to rapidly pulse a redstone torch tower
* Items can only be feed at levels where you have a comparator clock
Example Tower Designs...
ACtennisAC 'Easy Item Elevator'
Very simple torch tower. With a long extended over-clocking. This makes it slow to start, and a very long (noisy) over-clocking period at the end of an item run.
The taller teh tower, the longer the over-clocking period, and the more repeaters that is needed. It is not recommended for anything but a very small dropper tower.
MineCrafters987's (Rjblair77) Compact Vertical Item Elevator (with small over-clocking)
Basically a simple compact 'hosepipe' design with a very small (two extra block) clock attached. The Clock is great for small (under 20 block) towers, though as with all overclocked towers does add more noise to the tower.
Though I would not call it exactly 'simple', the video provides a very clear tutorial. The over-clocking is provided by a 'fade-out' comparator loop. Handles double hopper feeds, but will click a lot on start, end, or with only a single hopper feed. However a fade-out will set a limit on how high the over-clocking will send all items in the tower.
Benonthetubes Fastest Item Elevator?
Using a half-slab power feed (showing how to continue past 15 blocks), this tower uses a extremely large and complex over-clocking system so that it can drive the tower from bedrock to ceiling while running at double hopper speed.
Pulsed Item Wave Design
The next style was to slow the power pulse going up the tower so that it travels at the same speed as a single item travelling up the tower.
That is each item is pushed up the tower in sync with a power pulse, that is being sent up the tower.
The item and the power pulse moves together in a sort of wave, that the item rides, like a surfer on a ocean wave. The speed required of about one tick per dropper is quite fast. Though the overall item feed rate can vary with the design, due to clocking method and also perhaps redstone torch limitations. Each dropper (except the bottom feeder dropper) only ever has at most one item, and only for a very brief moment, as the item moves up the tower.
The power pulse typically uses a 2x1 alternating redstone torch tower, which provides the right delay between each dropper, though SabreMage, uses a pure repeater design, which could be used to make the frequence of pulses faster, and thus the towers overall speed. However his design still contains a redstone torch, which limits the item feed rate to the same as torch tower.
The droppers are typically powered by open redstone torches with no block on top, as this cleanly powers the droppers, without power overlaps. These powering torched are connected to the side of the torch tower, making a 4x1 or 3x2 tower size.
However you can also directly power droppers from the torch tower or though repeaters or even direct wire or redstone dots. The 'wave' nature of the power pulse will prevent power interactions within the dropper tower (though not at stacking points). However this method will cause extra clicking, especially at the start and end of a item run, and may make 'stacking' towers much more difficult.
There is a way to set up a 1 tick cycled torch tower without burning out the redstone torches, but that involves the pistoning of a redstone block back and forth over a single redstone wire, making it noisy. It works because the piston generated pulse is a 1/2 tick (1 game tick) out of phase with the normal redstone updates, so by-passes the redstone torch burnout test. This however may get fixed at some point.
Advantages
* Resource light (typically 3 torches per 2 droppers)
* No clicking if done properly
* droppers empty most of the time
* individual items move very very fast to top of the tower. Disadvantages
* overall item rate is limited by pulse rate, and torch burnout.
* tower can typically only have an even or odd number of droppers, depending on the clocking feed.
Example Tower Designs...
ToastedBaby torch dropper tower elevator
Uses a comparator clock, so multiple items can added at base. Speed is at a 2 to 3 tick rate to avoid torch burn out. It is perfectly silent.
The main tower is 4x1 wide, which allows it to be encased in a 3 block wide wall. or you can twist the torch tower (as in my photos) to produce a 3x2 'L' shape.
However this design needs to be an odd number of droppers high. Also note that the torches are on by default, so you need to be careful of nearby hopper pipes.
When stacking towers (for a mid-level item feed), the top torch on a mini-tower could be under where you add a comparator, or the block between the comparator and the dropper tower. This can cause power interaction issues.
AntOfThy Alternative Design to ToastedBaby's Pulsed Tower
(base circuitry) (power feed up tower)
This design is basically the same torch tower as per ToastedBaby's design, but the base has been redesigned, so that the first dropper is powered from the redstone torch (as a inverter), rather than a direct power feed from the comparitor. As such all the droppers unpowered by default.
The new power arrangement also means the tower is an even number droppers
high, and is now perfectly silent. The power arrangement does not extend
downward below the bottom-most dropper, removing any power interaction issues
and as such you can now 'stack' multiple towers on top of each other.
Unfortunatally the base circuit of the a tower 'stacked' on top will need to be rotated 90 degrees, as the comparator cannot be placed above the top-most redstone torch of the tower below.
Soenderups - Silent Elevator (demonstrated by CubeHamster)
Also uses a redstone torch tower to power a set of torches without blocks above them, so cleanly powers the droppers in pairs.
It is practically identical to the previous design but with an extra column of blocks with redstones dots on them. That column ensures dropper powering torches are off by default, and to me feels like wasted resources.
alfabitslp Compact Minecraft 1.5 Item Elevator
(base circuit) (power feed)
A pulsed torch tower design, but uses repeaters to deliver power to the droppers. However this power arrangements will also power a dropper below the one directly powered, however this dropper is normally still powered by the previous pulse (so no extra click).
An item feed limiter is used to ensure the tower does not generate stuck items due to the power overlaps that exist in the tower, but the result of this is a fairly complex base circuit that makes this design diffcult to install in space limited areas (which is a typical problem).
The power overlap, caused by the use of repeaters, also means you cannot stack these towers to provide a mid-level feed. If you try you will get about 1 stuck item per stack of items, appearing in the second dropper from the bottom of the stacked tower.
On the other hand by using a repeater to power the droppers, the final chest can be placed on a completely open floor at the top. That is something a redstone torch pulsed tower cannot do, without posibly leaving one 'hosepipe' item in the last dropper below that chest, by using a solid 'floor block' above the final torch.
SabreMage - MC-1.5.2 Item Elevator
Small clock, but large (very open) repeater based power feed to delay the pulse up the tower. Redstone powering torches, are placed on alternating sides, which wraps around the droppers on three sides. The glowstone and even support blocks in the design may be replaced by half slabs, to save on resources.
KMBKomhyr - Silent, Fail-Proof, SMP-Friendly Item Elevator
A very novel way of passing the pulse in a spiral up the tower while only powering one dropper each time.
The disadvantage is that droppers become completely wrapped by the redstone, though it does make it quite compact.
Draykke Devry 1.7+ Dropper Elevator
Another simple variation of the pulsed design with variations for odd number of items.
His even number variation however relies on a trap chest to power the last dropper on opening, so does not work for continued item transport. Also the trap chest is likely to cause a item jam if the tower is active at the time you open it.
His use of a repeater to power the base dropper will cause power interferance and thus preventing stacking of towers for multi-level item feeds. Finally his design does not include a clock, so if lowest dropper gets more than one item, say due to a chunk load glitch or multi hopper pipe feeds, it will become locked in a always on state.
This is a design I developed from the previous designs, that specifically allows you to stack a pulsed item dropper tower without power interference. It will stack neatly at intervals of any even number of droppers, and like all good pulsed item designs, is perfectly silent.
Also as the torches are sited to one side of the droppers, the comparitor for the next 'stack' (mid-level item feed) is not located above a redstone torch. This means the stacked towers base circuit does not need to be rotated as it is in ToastedBaby's Pulsed tower design.
Multi-tested, Single Clock Towers
These tower designs still run the whole tower using a single clock (so can be noisy), but the clock is only run while items are still in the tower. This is achieved by using comparators to test the tower at multiple points, and then sending that 'detect' signal to activate the clock. The the clock then powers the droppers. Typiclaly the clock is at the base, with the power signal running up the whole tower. the tower could also be run from a switch at the top of the tower.
This means items can be feed into the tower at multiple points, not just at the bottom, and the tower will detect them and clock the tower.
In one sense these are a sort of "Over-Clocked Tower Design", but without using a 'fixed' run time delay on the clock. This means the time the clock runs will automatically adjust to the size of your tower. As such it you want to make it taller, you can just do so, and it adjusts the run time accordingly.
In another sense these towers are just one step away from being a "Stacked Dropper Tower Design" (see next), and thus noise.
Of course this means the tower is not quite as compact as the last few design types, but certainly not as heavy on resources, or use as many supporting blocks as Fully-Tested Dropper Towers does.
Advantages
* Medium use of Resources
* Items can be feed an multiple points
* Timing automatically adjusts to tower height
* Clock only runs while items in tower
* More open circuit compared to normal fully-tested towers. Disadvantages
* Generally Noisy, especially if items are being feed high the tower.
* Items can only be feed at levels where you have a comparator clock
* Clock can stop/start as the last item reaches the top of the tower.
Example Tower Designs...
Whezolor Fully Tested, Single clock, Dropper Tower
This design has a comparator testing every dropper in the tower. These then feed a down signal to run the clock at the base of the tower, which powers the whole tower. As such no stuck items are possible. In many respects the circuit is fairly complex, especially at the base.
Unfortunately this means the tower has a large footprint all the way from top to bottom.
mrvdg (Merv Dog) Multi-Tested Tower
This is a much simpler version of this type of tower, with the main tower occupying a very small 3x2 footprint. It uses a torch tower to power the droppers, but also tests the specific spots (every 4 droppers) where items can be left behind to check if the tower is clear of items. That signal is then sent down the tower to run the clock.
This makes the design very simple by comparison to Whezolor's, and actually even pre-dates Whezolor's more complex fully-tested design by a month or so. Kudo's to Merv Dog.
The clock at the base is quite simple, but I think could be compacted a little more by using a 1-wide vertical clock, rather than a flat 'ground' clock. But that is just packing.
Stacked Tower Designs
These are designs that actually rely on stacking smaller towers of more than one dropper, to achieve some purpose. This is typically used to ensure the tower is completely cleared of items, but the stacking can also be used to reduce over-clocking times (if any), and thus the amount of empty dropper clicking (noise) that most designs above generate.
The biggest advantage of using stacked towers is that you can feed items at many levels up the tower. However you may still need to watchout for "Item Jams", that can result from a mid-level item feed. Because of this a design that self-clears has a added advantage.
Advantages
* medium resource requirements
* no items left in tower (generally)
* multiple points for an mid-level item feeds
* great if the stacking corresponds to you build's floor levels
* Only a few clicks, if any, in each mini-tower, for each item run Disadvantages
* may not be perfectly silent, (but low noise)
* Item feeds only at specific points.
* may item jam on heavy mid-level item feeds.
Note the video only shows the tower as part of a larger build of a storage silo. Jump to 7:10 to see the 'droppervator' details.
This tower is different in that it actually relies on quasi-connectivity to convert a single dropper powering method into a 2 dropper powering method, allowing it to stack every two levels. It is not really light on the redstone, but is still a lot smaller than a Fully-Tested Dropper Tower. As it does not use redstone torches, it can use, and probably relies on a faster clocking speed. Timing measurments still to come.
In towers with a even number of droppers, a item will be left in the last dropper, but it isn't stuck, and will be replaced by the next item that comes up the tower. For odd numbered towers, slightly different circuit at the top, will not leave any items in the tower.
It is completely silent in the middle of a item run, but does tick a little at the start and end of a run due to overlapping powering. For the same reason, I would not recommend directly stacking this tower with any other tower design.
timeofsouls Max Speed Dropper Tower Returns!
This design uses stacked 'mini-towers' each 3 droppers high. A very small over-clocking circuit is attached to the normal comparator test. That way the tower is pulsed one extra time at the end of the item feed, which keeps each mini-tower clear of stuck items, while avoiding linkage problems when they are stacked.
The circuit is very small relative to other over-clocked designs, but as mentioned is repeated every three levels so is more resource heavy and volume heavy than other over-clocked towers. But it is much lighter than other designs with comparators on every level or every second level, and clocking circuits are easy to get to for adjustments. Especially in survival minecraft.
It is also very fast and as such needs a double hopper feed to keep it working at peak performance. With such a feed it will run silently, with clicks at the start and end of a large item run.
The screenshots shown are slightly more compact alternative circuit layouts. It is still the same circuit, but with the secondary comparator clock flipped to reduce its footprint slightly (4x3 area).
In one variation to the design to extend the half-slab power feed to make each mini-tower slightly taller. You will then need to also extend the clocking, and thus the increase the amount of clicking noise at the start and end of a run. That extendability can be important for towers that are not a multiple of 3, or you need hopper inputs at a different level. Just watchout for power overlaps between tower stacks.
This is another variation of the "2x1 dropper hosepipe design". With a slightly more compact clocking and power feed into the redstone torch relay tower. Each mini-tower is 6 droppers tall which is a good multi-floor spacing.
The key to the design is noting that the first item that remains in the 'hostpipe' design is 6 droppers up. At that point the tower is stacked meaning the item will now be immediately detected and sent further up the tower by the next comparator clocked 'mini-tower'.
In other words this is a 'hosepipe' design that is stacked in such a way as to leave no items in the tower. Thus is no longer a hose-pipe design.
Yes there is some clicking at the start and end of item runs but it is very light by comparison to over-clocked designs. Also 'stuck' or 'jammed' items will in most cases slowly self-clear the mini-tower with time, just as they do in the normal "2x1 hose-pipe design".
The clocking circuit shown above also has a slightly smaller footprint, but at a cost of extra depth to the clocking circuit.
Final notes and Recommendations
My suggestions... depends on your needs...
For simplicity use the Compact Dropper Hosepipe Design
For light on resources, use Compact Dropper Hosepipe Design
For self-clearing of stuck/jammed items, a Compact Hosepipe Design
For immediate delivery, anything but a Hosepipe Design
For multi-level feeds, one of AntOfThy's, Designs (see below)
For speed but mostly silent, use timeofsoul's stacked tower
For total silence, use a Pulsed Item Tower, or Tilable Hose Pipe
For tilable dropper tower, only the Tilable Host Pipe (see below)
For extreme bulk transport, use a glass item elevator! (see below)
For extremely tall towers, use a glass item elevator! (see below)
My recommended designs (developed from this extensive study)...
Tilable Hose Pipe Dropper Tower
A simple tilable hosepipe tower, though needs 2 hoppers. It is silent but has a cost of leaving one item 'in-the-pipe' at the 5th dropper and every 4th dropper after that. However you cannot stack two of these towers directly on top of each other.
If space is not an issue or you need mid-level item feeds, look at the next recommendation.
AntOfThy's Stacked Hosepipe Tower Design
(base) (stacking) (overview)
Though this tower is not silent, it is not overly noisy either. It can be stacked, and if stacked at a 6 droppers no 'in-the-pipe' items will be left in the tower.
This tower will very slowly 'self-clear' "Item Jams" by one item at end of each item run. That is the cost of the extra click!
AntOfThy's Pulsed Item Stacked Tower Design
(base) (power & stacking)
This tower is perfectly silent, and will stack at any even number of droppers, and as with other pulse-wave designs does nto leave items in the tower.
The cost of this is that it will not self-clear "Item Jams" caused by backflows, or vertical chunk load issues. They will simply 'remain' until manually cleared.
test137E29's piston-less glass item elevator
This is a game changer for item elevators. No pistons, no redstone, and with packed ice, no light-ice problems, no noise, very cheap, and looks so cool too. This elevator is probably the better solution for any situation involving large numbers of items, or for moving items up more than 20 blocks, even if it means having a dropper (or two) feeding the items being transported into a water stream.
The same video also illustrates designs for "instant dropper towers and pipelines" however while these are 'instant' they are so heavy on resources, especially gold rails, and such not practical until you have a gold farm. I doubt many players would want to use them. Still it is available, and who knows, may be usable as a multiplexed instant signalling method.
Signed AntOfThy, Last update 26 June 2014, MC v1.7.9
First... you just posted your design without even reading the original post!
And yes your tower works. It is actually almost identical to ACtennisAC's design. It is mostly a 'pulse dropper tower' but with a small over clock to handle any stuck items.
But I very much doubt you can 'stack' two of these to add a extra feed in the middle! At least not without a lot of effort.
Note a torch tower like this clocks three droppers on every torch. WIthout the over-clocking (which produces that final click) the arrangement of power handling will generate a stuck item. On other other hand side mounted set of torches (no blocks above the torches) will smoothly and cleanly power only two droppers per pulse. That is a single item move up two droppers on each pulse (reason why some designs can handle a double hopper feed).
Now you mention in the video you can build it up higher.. Have you tried? I doubt with the amount of extra over clocking provided, you would get all the itmes to the top of a 100 block high tower. But then would you want to.
I suggest you figure out how to 'stack' two of these on top of each other.
In summery: it is likely to be a good reliable design that works. But you probably can not directly stack two of them without a hopper, to isolate the power handling. And it clicks.
Single torch tower powered dropper tower would actually make a good 'Hose Pipe' design. That is some items always remain in the tower, but will move upward as more items enter at the bottom.
PS: I have a personal preference to avoid a tower with any sort of clicking, it speaks to the engineering part of me of in-efficency in design. Though I understand they work and include them in my study. I also like adding a lamp every block (off when not in use) to show when the the tower is running. :-)
First... you just posted your design without even reading the original post!
And yes your tower works. It is actually almost identical to ACtennisAC's design. It is mostly a 'pulse dropper tower' but with a small over clock to handle any stuck items.
But I very much doubt you can 'stack' two of these to add a extra feed in the middle! At least not without a lot of effort.
Note a torch tower like this clocks three droppers on every torch. WIthout the over-clocking (which produces that final click) the arrangement of power handling will generate a stuck item. On other other hand side mounted set of torches (no blocks above the torches) will smoothly and cleanly power only two droppers per pulse. That is a single item move up two droppers on each pulse (reason why some designs can handle a double hopper feed).
Now you mention in the video you can build it up higher.. Have you tried? I doubt with the amount of extra over clocking provided, you would get all the itmes to the top of a 100 block high tower. But then would you want to.
I suggest you figure out how to 'stack' two of these on top of each other.
In summery: it is likely to be a good reliable design that works. But you probably can not directly stack two of them without a hopper, to isolate the power handling. And it clicks.
NOTE: Single torch tower driven towers is one of the few tower designs I have not (yet) closely looked at, simply because, after figuring out stack tower power linkage faults as being a major problem, such towers did not seem ' good' to me. I do plan to look at them in the next day or so, though I have a feeling the power pulsing upward will out pace the items in the elevator.
That said. I believe a single torch tower powered dropper tower would actually make a good 'Hose Pipe' design. That is some items always remain in the tower, but will move upward as more enter the base. Probably less items than the other 'host-pipe' design currently shown (picture only) in the OP.
PS: I have a personal preference to avoid a tower with any sort of clicking, it speaks to the engineering part of me of in-efficency in design. Though I understand they work and include them in my study. I also like adding a lamp every block (off when not in use) to show when the the tower is running. :-)
After some testing of a single block torch tower next to a dropper tower (such as in Rjblair77's) reply...
Yes the redstone signal out paces the items in the tower. However because an item moves two droppers ech time a torch powers on, and each torch is alternative on/off up the tower, a full pulse (on then off) will move items upward four droppers at a time.
That does make a great 'hose pipe' design, even without over-clocking.
Here are two variants we came up with on the server I frequent. They may have been discovered before, but as far as I'm aware these were developed by the users NickBambridge and I. They rely on the hopper clock, which allows for an extremely slim (1 wide) and tileable, should you need to, system. The second variant is not tileable due to the introduction of a piece of redstone dust, but is slightly more compact. Both systems can handle any load, but leave a single item in the pipe (not stuck, it gets flushed when new items enter).
Imgur album link (two images): http://imgur.com/a/MtSr7
The single torch method of distribution can be changed, but is our personal favorite because it is compact and doesn't burn out with the hopper clock. We've used several of these in our server's iron farm and after filling 18 double chests with iron ingots, there are still no issues whatsoever. Multiple feeds can be managed, but would require some editing that I'm too lazy to provide at the moment.
Here are two variants we came up with on the server I frequent. They may have been discovered before, but as far as I'm aware these were developed by the users NickBambridge and I. They rely on the hopper clock, which allows for an extremely slim (1 wide) and tileable, should you need to, system. The second variant is not tileable due to the introduction of a piece of redstone dust, but is slightly more compact. Both systems can handle any load, but leave a single item in the pipe (not stuck, it gets flushed when new items enter).
Imgur album link (two images): http://imgur.com/a/MtSr7
The single torch method of distribution can be changed, but is our personal favorite because it is compact and doesn't burn out with the hopper clock. We've used several of these in our server's iron farm and after filling 18 double chests with iron ingots, there are still no issues whatsoever. Multiple feeds can be managed, but would require some editing that I'm too lazy to provide at the moment.
It is a nice design, an essentially the same as the just added 'Compact Dropper Hosepipe Tower'. Just with a more complex hopper clock to do the timings and to create 1 extra pulse on the end. Much like Rjblair77's Tower Design has a extra clock (over-clocks a little longer)
As you mentioned this type of power feed system will leave 1 item for every four droppers (not stuck, just in the 'pipe'). You should have 2 items in this tower, but over-clock the tower by one more pulse. If you extend your tower up higher you will have more items left in the tower 'pipe'. It also 'clicks' even in the middle of an item run, though in this case the extra clicks slowly 'self flushes' any extra stray items.
A big advantage I see for having a separate clock, is that you can add a lever (or even a button) on the block the comparator points to. When you activate it (for a short time) the items in the tower will then be flushed out. Useful if you want to push all items up to a mine cart when leaving the area for a while.
Being tileable is another advantage, and kudo's to you.
Again you may like to look at how to 'stack' your towers, so as to provide multi-level item feeds, such that does not cause a item jam around the feed. Especially irregular feeds that are hard to test without a couple of mob systems nearby. That is my next line of inquiry with this type of tower.
I looked into stacking them and unless you don't mind staggered towers, the torch "hose" method won't work. Otherwise I can simply use a different method of signal propagation (it takes little modification to change from the torch method to others).
That is what I figured. and it is this aspect that causes 'problems'.
(a number of designs are really stacked mini-towers).
However if you ensure that the powering droppers do not overlap there should not be a problem. (see original Post).
I will look at stacking towers of this sort and if I get it working I'll post a image of the stacking point. It is likely you will only be able to stack at either an odd, or an even number of droppers, without needing a isolating 'hopper linked staggered tower' stacking method.
I also have to get a photo of the stacking (even number of droppers) for the Pulsed Tower Design I now use.
Okay the stacking was not so hard.
The key was to place the mid-level feed on the level one block above a restone torch.
BUT remove the block above that torch so it does not feed power into the upper mini-tower.
Now the only way I locked this up was to add many stacks of many different items directly into the mid-level feed dropper. When that happens items in the dropper below may become 'clogged' and stuck. however for a single hopper feed at the mid-level this is not going course this to happen very easily (hoppers only can hold 5 different items, droppers 9 different items and randomly send items up)
But that is a problem for any stacked tower.
The problem is made worse by the fact that droppers and hoppers always stick items in either the first available free slot, even if there is a incomplete stack of the same item somewhere else in the container. that is they can fill multiple slots with the same item.
Note this does not happen when users 'shift-click' items into such containers, only with hopper or dropper feeds into the containers. I consider this to be a bug.
I think this topic might garner more responses if you include a visual example of each category of dropper tower. I have several different designs that I use depending on what I need them for, but I'm hesitant to post them because I'm kind of getting lost in all the text ("Well, I'm 90% sure he's talking about ____, but I'd really like to see just to be sure I'm not submitting something he's already covered"). I'm sure there are at least a couple others that feel the same.
I have replaced 'image links' with 'thumbnail' links, so in at least those designs you can see what the image is showing, if not the fine detail.
The other links are mostly youtube video links, and youtube does not provide a nice thumbnailing method.
UPDATE: I also rebuilt almost all towers on the CubeKrowd server, so people can go take a look. Also more screen shots, and of the various towers and their respective parts.
Added new category of dropper tower designs... Stacked Towers
That is tower designs that actually relies on regular 'stacking' of the towers.
Currently two designs stacked every 3 (timeofsouls) and 6 (antofthy) blocks.
I think this topic might garner more responses if you include a visual example of each category of dropper tower. I have several different designs that I use depending on what I need them for, but I'm hesitant to post them because I'm kind of getting lost in all the text ("Well, I'm 90% sure he's talking about ____, but I'd really like to see just to be sure I'm not submitting something he's already covered"). I'm sure there are at least a couple others that feel the same.
More images of the various types of dropper towers, methods of powering, and a starting image of what I consider one of the best (not overly complex) designs so far to come from this study.
I hope this helps improve responses, as this is an area that can use more attention, considering just how useful dropper towers are.
Yesterday YourTuber, Drakkart, posted a variation on the Dropper Hose-pipe Design I discussed as a basic tower methodology, making use of the principle that leaving items in a tower is "Not a Bad Thing", it just means the tower remains silent, and items will be delayed but will come out.
Having now looked at just about every dropper tower design out there. Building and testing them, attempting to stack and avoid power interference. Many revisions and updates of the original post. I can say the main article is complete.
So make use of it. And letting me know what you think. And above all, some credit for the work I did would be nice. ;-)
Note that I have rebuilt practically all the Dropper Towers on my
creative plot on the CubeKrowd MineCraft FanServer... cube.jl2579.net
login to the server, type /cr, and then /tp -4900 30 -6000 (you are in creative do don't worry about falling).
We are recoding the cubekrowd server currently, but we are working on getting our creative world back online ASAP. Also Members+ can use /plotme home NAME to get to your plot, Guests can do a tp request, most of our members are kind enough to help getting to that location so you don't have to fly out there(That would be absurd.)
But again, we are currently upgrading the server to make it work better, so it may be a couple days before it is available to work on, and there may be a need to move your build to the new creative world as I believe the chunks of the world you built in had some weird corruption issues.
We are recoding the cubekrowd server currently, but we are working on getting our creative world back online ASAP. Also Members+ can use /plotme home NAME to get to your plot, Guests can do a tp request, most of our members are kind enough to help getting to that location so you don't have to fly out there(That would be absurd.)
But again, we are currently upgrading the server to make it work better, so it may be a couple days before it is available to work on, and there may be a need to move your build to the new creative world as I believe the chunks of the world you built in had some weird corruption issues.
Bump, no offense but seriously. What does that have to do with this topic?
Rollback Post to RevisionRollBack
[a href="http://cur.lv/gw3nw" target=_blank>[img src="https://www.chickencoins.biz/img/chickencoinbanner.gif" alt="Enjoy every 10 minutes!" style="width:550px"] [/a]
http://www.minecraftforum.net/topic/1816466-dropper-towers
NOTE: This image is only an example of one of the better designs. Many designs are looked at below.
First a bit of philosophy...
Dropper towers are something that people are using as a means of creating a item elevator ever since you could face a dropper upward, and glass item elevators became so glitchy. (Update: see the piston-less glass item elevator by "test137E29", link at end of post)
But droppers are not really designed for 'piping' items (though in the first few snapshots of v1.5 they were), and as such there are problems when used in this way.
That said this was written for Minecraft v1.5.2 to v1.7, in case things change, though I am updating this document as new facts, techniques and designs come to light.
After studying many dropper towers, building many on various servers, multi-player and single-player, I came up with these notes, showing just how complex dropper towers can be to get working correctly, what designs actually do work, and what did not. But more imprtantally why designs fail.
NOTE: You can see many of the designs on my CubeKrowd Creative Plot. This world is open to everyone, and anyone is allowed to get a creative plot for there own experiments and or 'member application builds'. To see these designs, minecraft login to "cubekrowd.net" go to the 'creative plot' world ("/cr" from lobby), and jump to my creative plot ("/plotme home antofthy"). I lost many of the early builds in a major plot reset some time ago, but have been rebuilding most designs on my plot since that time.
Comparator Clocked Droppers (not towers)
The following shows a number of methods of using a comparators to clock a dropper, (not a dropper tower)
And many more types of dropper clocking circuits are shown in Imgur Photo Album - Dropper Circuits
The purpose of these circuit screen-shots is not to show what is 'good' or 'bad' but to show just how much variation is possible. Basically there is a lot of ways you can arrange the comparator circuits.
Most of these circuits work well for single droppers, or even dispensers, but generally do not work (as explained later) when used for dropper towers. This is where most people have problems in designing and building their own tower.
Warning: If a block is used between the dropper and comparator that block should not become powered. Doing so may result in a comparator lockup or other undesirable feedback loop. However I and many others have powered this separation block in some designs clocks without problems. Caution is recommended.
(This is a must read if you really want to understand and fix dropper towers)
In the previous section we saw that there are many methods of powering droppers, but what effects do these have on a tower of droppers.
So here is what I learned from many experiments different ways of powering a dropper tower. I did not look at a sequence of sideways or downward facing droppers, as these are better handled by hopper pipes.
Note that exactly when dropper is powered does not always make a lot of sense, and some of these may be 'fixed' in later updates. Then again, they my not be fixed.
But unlike most other powered devices, it is not just what is powered that matters, but the exact order in which they are powered by the signal, as well as Quasi-connectivity powering effects.
power is transmitted on to dropper.
OR a redstone dot on a block next to a block next to the dropper tower,
powers only dropper next to the solid block. (weakly powered dropper).
This is the ONLY methods that will activate single dropper!
But.... Due to Quasi-connectivity effects, the dropper below may also become powered due to some type of update effect, and then remain powered until updated again after the power is removed.
This becomes a major problem in Fully-Tested Dropper Towers (see below). It can also become a problem when stacking towers (which is essentually what fully-tested towers are.
This method is not recommended, except in Fully Tested designs, where you really have no choice about it. It is just another reason that quasi-connectivity is simply a BAD IDEA.
On the other hand, purpledragonnuke published a dropper tower, as part of a larger storage silo video which makes use of the quasi-connectivity to produce a Stacked Tower design (every two layers).
the dropper above is not powered! Only 2 droppers are powered!
Now while a tower of lamps (see image), will only show one lamp powered, 2 droppers are powered! The lower dropper will receive power first, meaning the item in that dropper will get moved up BEFORE the dropper next to the torch moves its item. That means if there is only one item in the lower dropper, and none in the one next to the torch, that item move up 2 droppers, to the unpowered dropper above the torch.
In other words if a single item is anywhere in these two droppers, it will always ends up in the next dropper in sequence. This makes this powering method the only one that only powers two droppers. Also if extra pusle is recieved the droppers will be cleared of any 'extra' item that make have become stuck. This is important in some stacked and over-clocked designs.
Note that the lower dropper is actually being powered by quasi-connectivity, but is also being updated immediately, and as such does not become activated due to uncontrolled through BUD effects.
powers 3 droppers, (one above and below)
The middle dropper (being feed directly will be powered first, then the other two droppers above and below. As such only an item in middle dropper can jump two droppers. Any item in the lower dropper will only move up one to the middle 'directly powered' dropper.
Warning quasi-connectivity effect may actually cause the dropper two below from also being powered if a it recieves a redstone update.
will also power 3 droppers, but in a different order to the previous one!
The lower and upper droppers will be powered first, followed by the one in the middle next to the wire or torch. Only the item in the lower dropper can jump two droppers on a single power pulse.
Note that the order is different between a wire feed on a solid block vs a wire feed on a half-slab!
This is a technique known as a 0-tick pulse, and is caused by the redstone blocks being pushed by the pistons to become a entity. While the redstone block is an entity, it can not power the droppers, and as such droppers become momentarily unpowered. When power is restored it is restored from bottom upward within the same tick, thuch transporting an item all the way up to the top all within the same tick.
I have yet to see a full design based on this technique. Probably as it is noisy, and limited to the 12 block push limit of pistons.
Ideally when powering droppers you do not want to hear any extra 'clicks' during a full item run, as it means a dropper somewhere is getting powered (if not already powered) without items. Though you may do this on purpose at the start or end of a item run (see below).
Note that it is '3 dropper powering' methods that generally cause problems in most tower designs. That is because you either need 2 ticks to move an item through the 3 droppers (with extra clicks), OR you end up with overlapping powering of the droppers, which can cause timing problems and power interferance patterns, especialy when trying to stack towers. These problems are discussed in more detail below.
Because of this almost all perfectly silent dropper towers, especially at the start and end of a run, use the redstone torch 2 dropper powering methods, even though redstone towers burn out if driven faster than a 3 tick cycle.
UPDATE: Recent confirmation from ZipKrowd members: Kavo, and Panda has shown that redstone torches (and many other redstone input devices) are being effected by random ticks, causing the normal torch update delay to be short circuited at random! This is disastrous for dropper towers that rely on some type of redstone torch tower, as the timings might go wrong every now and then.
The result, as as been seen on some long running towers on multi-player server, is that items will be occasionally left in a dropper. This is not critical for a "Dropper Hose Pipe Design " as these tend to automatically self-clear, a random item, but for a silent "Pulsed Item Wave Design" this is very bad news as it will every so often leave an item in one of the droppers until manually cleared.
Please go to the Mojang BUG report MC-56541 - Redstone Torch inconsistent timings and vote to get this issue fixed.
No clock lockups
First, if a comparator does not run a clock of some kind, then two items in the dropper being tested will cause the comparator test to 'lockup'. For example, in GenerickB's dropper tower, without a item feed limiter it will fail. I will not say much more on this as the cause of this problem is obvious, and not really a 'stuck item', just a lack multi-item handling using a clock of some kind.
As such some type of clocking loop is typically essential in a reliable design, though there are designs that don't need it.
The Classic Problem Dropper Tower
This is design that has been re-discovered by many people even without realizing that it has already published, many, many times before. Who discovered it first does not matter as they are such an 'obvious' design.
Examples.
MineCraft101 web site, (The LAST dropper design)
http://minecraft101.net/redstone/dropper-elevator.html
fennoman12
Yes they work, but will fail in random spaced input and multi-level feeds.
Basically you take a standard 'clocked dropper' method (see above) and use it to power the droppers using a direct wire feed or repeater. Both of which will typically move an item up two levels to the next 'comparator clock'.
Again these work, but they are not reliable!
Power Interaction
The real problem is that power interactions can cause an item to end up in unexpected dropper. One that does not have a comparator to detect them. When this happens an item will remain in that dropper, though the actual item itself may be replaced by other items passing through the tower.
This generally happens around the point where two comparator tested 'mini-towers' (typically only 2 high) are stacked (see typical examples above).
When power interactions extend beyond the individual stacked mini-tower. The stacked tower can clock at a different rate to the tower below it, especially when items are delivered with irregular pauses, or more items get feed in at the higher level. It may even be caused by players leaving and entering chunks, or moving up and down a very tall tower.
The rate at which an item gets stuck in many cases may only be one item per stack, or it can in very bad cases be half the items in a stack. It does not matter if the items are all the same type sort, many different sorts, or even non-stacking item. For example I threw 3 double chests of bows (collected from mob drops) through one tower design, and had 3 bows get 'stuck', in the upper sections of the tower.
Note that once an item is stuck in a tower, it does not mean it remains in that specific dropper. Other small pauses in the item feed, and/or timing disruptions can cause a stuck item to move and drift slowly upward, especially in high volume towers. These types of towers will typically 'self-clear' stuck items over time, hopefully at a rate faster in which items get stuck.
These timing issues can be very common in a item feed from a mob system, or in towers where users throw many different items into a hopper feed at higher levels, while items are coming up from below. Basically the towers typically fail in a practical working base of operations, but work prefectly in ordered tests such as in a creative world.
The stuck item rate is rare enough that the towers will typically pass the testing phase, and only start failing when placed in a more practical situation. As a result, designers often think they find a simple reliable design, and immediately publish it, without further testing in a more practical environment.
If it is discovered, designer will typically give up on stacked designs, and work more on a simpler single clock, base feed only design, that most of the reliable designs follow. But these are not always the most useful, typically being noisy or have no mid-level item feed points.
Addendum...
There was one other problem I saw that was a cause for concern. It may however have been been a purely random glitch on a SMP server on whcih I was trialing the dropper tower.
I saw a single item that was 'flip-flopping' between the repeater powered dropper, and the dropper two above. The dropper with comparator was being directly powered by a repeater.
Opening the dropper showed that one item (gunpowder) appearing, disappearing and re-appearing again as it jumped back and forth between these two droppers, with the comparator clock constantly attempting to send that item further but failing to do so for no apparent reason. That is the item moved but was constantly restored back to where it was, causing the comparator to try again.
When another item was put in, the problem fixed itself without becoming stuck. This only happened once and I don't use that design any more (due to power interaction issues when stacking).
Most of the designs that have been published only lets you feed items at the bottom of the tower, where a single comparator runs the tower. That is understandable as these designs are resource light and often have few 'power interaction' issues to cause items to become stuck.
But you often want to add a feed into the middle of a tower. One way is to have an expensive hopper pipe, just going down to the bottom, simply to feed items back into the tower, so they go to the very top. But that is often thought of as being nonsensical. Though this does work and is a very clean solution.!
As a result you generally want to make two separate dropper towers, and stack them on top of each other. Or putting it in another way, you want to break your dropper tower into two separate comparator checked and clocked towers, that is stacked on top of each other. New items can then be feed into the middle of the tower, at the base of the stacked dropper tower.
Alternatively you may want to break a tower into two or more sections simply to reduce 'over-clocking' requirements (see below) and thus reduce excessive clicking at the start and/or end of an item feed.
But as soon as you break a tower into two, you run the risk of the stuck item issue, due to power interaction problems. That is by breaking the tower into two, many working designs will suddenly cause items to become stuck, either in the dropper one below the comparator, or somewhere just above that comparator.
Designs that rely on a steady item feed (no comparator driven clock) will also break as an extra item feed can now over feed such towers, causing even more problems.
One simple solution to this problem, and most other stuck item problems, is to completely isolate the mini-towers. To do this replace the destination dropper with a hopper and pipe the items to a completely separate dropper tower, perhaps just one block further over. That is each stacked tower is displaced horizontally by at least a single block using a isolation hopper).
For example this image posted to the forums, show multiple 2-dropper 'towers' which are staggered using hoppers to isolate the dropper powering arrangement that was used.
If you also add a buffering double chest, then the new tower will start one block lower (hoppers can only suck items from a chest above them, so the hopper feed into the next tower will be one block lower).
These solutions work great, but a zig-zaging series of towers can look messy
in what would otherwise be a single long tower of stacked droppers. But in
some situations, this is recommended because of the extra buffering the
isolating hoppers (and chests) can provide (see "Item Jams" below).
Note that using isolation hoppers is also more resource intensive due to the extra iron needed for isolation hoppers.
Be warned that, power effects can also extend to the hopper that the final dropper may be feeding. That is while the final dropper is receiving power the hopper above it may also receive power and thus will not pass items on to the next hopper (or chest).
This is typically not regarded as a major problem as long as the tower powering method does not leave the tower in a powered state by default. But as slowing the item transport away from a dropper tower can cause item jams (see below) it can be just as important to ensure the power does not extending beyond the top of the tower, not just at the bottom of a tower.
The better solution is to ensure that you never have an overlap in dropper powering between the two stacked mini-towers. That is what the previous power feed guide is for. In this way dropper towers can be stacked without needing isolating hoppers or item buffers.
A typical way of doing this is to have a final redstone torch in a tower does not have a final block above it. That is ensure to power 2 and only 2 droppers at the top of the lower tower (item moves up 2 droppers on one pulse).
For example a typical single torch tower "Pulsed Item Design" (see below), only needs to NOT have a block placed above a torch, to prevent power overlaps. I do this on purpose in my own Stacked Tower Design.
But remember you cannot place a comparator immediately above that redstone torch. Also you cannot move the comparator one block away from the dropper as a comparator needs a solid intervening block, and it is this block you wanted to remove. As such when stacking the second you must either have the redstone torches on a different side to the comparitor, or rotate the clocking circuit 90 degrees for each tower stack.
One 3 dropper powering example which solves this power interaction problem is by timeofsouls (see Stacked Tower Designs below). This is designed so that the clock generates one extra pulse on the the last item (due to an longer repeater delay). This ensures all items in each mini-stack of three droppers are sent up to the next tower. Of course it does cause clicking as each mini-tower clears. But that extra pulse will also clear any stuck item that may appear in the tower (see next section).
There is another way items can become stuck and leave a large number of items in a untested dropper, and this does not involve any type of power interaction problem.
If the container block the top most dropper is feeding items into (which may be the dropper of a mini-tower that is stacked on top of it) does not have a slot the item can go into. When this happens the item simply does not move and so becomes 'stuck', in that top most dropper, which is typically not comparitor tested.
The fact that droppers randomly pick items (and rightly so) could mean that one time an item can be pushed, but another time it can't, which introduces randomness into the system. Hoppers Piplines can also mix up items when a different item is suddenly recieved in its first slot, and that also randomize and shuffle item types that is entering the dropper tower.
The problem is made worse by the fact that droppers and hoppers always stick items the first available free slot, even if there is a incomplete stack of the same item somewhere else in the container. That is they can generate multiple partly full slots with the same item, and thus preventing that slot from being available to some other items, even though it could (with some inventory management) accept that item.
Many times I have looked in a jammed hopper pipe to see all 5 slots containing a small number of the same item. That is the hopper was not actually full, just has no slot available for some other type of item, and thus preventing any feeding hopper/dropper pushing in some other item.
Note this 'put in first possible slot problem' does not happen when users 'shift-click' items into such containers, only when a hopper or dropper feed items into containers. I consider this to be a bug.
This is a buffering problem. Basically the destination container, be it hopper, dropper, chest, or their minecart variants, is not able to accept the item being 'pushed' into it.
In stacked towers this is typically not an issue, as you are feeding items to it at the same rate that the tower above is handling them. It however can become a problem if that upper mini-tower is also receiving a lot of varied items from another source. For example from a dump of a players inventory, or a large storage chest of adhoc items, or even a second mob system.
The situation becomes worse when the tower is pushing items into a hopper, which only has 5 slots, and so while the dropper can select from 9 different items, the hopper and only recieve 5 different types.
A double chest however has a lot of slots, and so provides a ideal buffer for situations whenever too many varied items are involved.
One other solution to this buffering problem is to add one extra comparator test and clock to just the top most dropper of the lower tower. This was presented as part of a item sorter in
IronStoneMine Compact Automated Item Sorting
This is not I believe a ideal solution as it only provides a small buffer (the top most dropper) to items not able to complete their journey. IronStoneMine's dropper tower however was also only 3 droppers high, non-stacking, and not dealing with too many different types of items in his design. As such I doubt that his 'dropper buffer' would also become full.
Over-clocking the tower can also be a solution. Even if one run of items does not fully clear the item jam during the over-clocked period, successive later runs will slowly clear those stuck items. For this reason a small amount of over-clocking, even in tower designs that normally do not need it, may be a good idea. If you don't mind a small amount of extra clicking at the end of an item run.
A "fully comparator tested tower" which uses a comparator test and also clocks on every dropper, will also never experience a item jam. If an item jam develops, the tower will continue to try moving the items until the cause of the problem is cleared up the line.
Fully Comparator Tested Tower
This is the first 'obvious' design to tower builders and one that is also typically rejected very quickly (perhaps too quickly) due to circuit packing problems.
Basically you use a comparator to test each and every dropper in the tower and then power the dropper if it has any items.
You will never 'lose' items. As at no point can an item exist in a dropper that is not tested. It also does not matter if multiple droppers get powered, as skipping droppers, or pulling items from below cannot result in stuck items. It does not matter where the item ends up as all droppers are tested.
However stacking the circuits at every level is a very difficult problem. First you can only place a comparator, repeater, or even redstone wire on a supporting block that will use up space in the circuit below. Secondly any raw redstone wire supported by a solid block (though not a half slab) will power that block, which can in turn can power the circuit below.
Because of these 'support' and 'packing' problems you cannot simply stack two identical circuits on top of each other. And so you will need at least two different circuits (perhaps the same circuit simply rotated 90 degrees) from one level to the next level. This will make the resulting redstone very heavy and dense, limiting access and perhaps even wrapping completely around the tower on three or even all four sides.
If each each circuit is not clocked (as in GenerickB's design) you must restrict the item feed to one at a time, as a comparator may become locked up by 2 items, with one getting sent on, while the other keeps the comparator powered, preventing further action.
A major problem with fully tested dropper towers is the smooth flow of items through the tower. If the clocking repeater is set to 1 tick delay, the items in the tower start arriving in spurts with significant pauses between. That is the items arrive in a irregular way, in the form of a interference pattern. That inturn reduces the overall speed in delivering a stack of items, by around 50%. All the items will still arrive, as you cannot lose items in a fully-tested dropper tower, just not as quickly as expected.
The problem seems to be caused by the dreaded quasi-connectivity problem that not only plaques pistons, but also dispensers and in our case droppers. That means the clock not only powers the current dropper, it also powers (with redstone updates) the dropper below the current one, effectively clocking two droppers, when only one dropper should have been powered.
Note that this does not cause items to be stuck, as that is imposible in a fully-tested tower, but it does cause severe miss-timings between each dropper clocked layer, that in turn causes delays in comparators detecting and clocking items through the tower. So far only one specific clocking method has been found which has a timing that prevents this problem. See "Fish Bone Fully Tested Dropper Tower" below, though it is likely to break due to update timing changes in 1.8.
The simplest solution to prevent this problem is to use at least a 2 tick delay in the comparator clocks, which causes a smooth flow of items through the tower, and is a lot faster than if you had used 1 tick repeater delays in most fully-tested tower designs. As mentioned the exception is the "Fishbone Tower" below.
Advantages
* PERFECTLY SILENT - If you only power one dropper!
* Items can be feed in at ANY point in the dropper tower (if clocked)
* Stuck Items are not possible, as they will be found and handled.
* Item Jams (due to the destination being 'full') will clear automatically
Disadvantages
* RESOURCE INTENSIVE - very dense redstone use at every level
* Very large foot print on every level in the tower.
* Redstone has to 'interleave' to allow a comparator check on all droppers
* So much redstone can make it hard to add mid-level hopper feeds.
* Quasi-Connectivity interference effects can slow item rate by 50%.
Example Tower Designs...
GenerikB Minecraft Item Elevator Tutorial (and challenge)
A highly compact interleaving of the testing circuit, while only powering one dropper at a time. There are no clocks, so if a dropper some how ends up with two items it will become locked in a permanent on state.
To prevent lockups a special redstone 'dot' is added next to the input hooper to slow the feed to only one item at a time. Limiting item flow also spaces the items in the tower, and prevents BUD, or other timing interference pattern effects.
This means you can not add a extra mid-level item feed. And it becomes especially prone to an item jam, which will permanently shut down the tower. Bud effects from block updates next to a running dropper tower can also have a devastating effect.
The moral of this example is that comparators not only need to test the droppers, but they must also should clock the droppers when multiple items are present.
CubeHamster Silent Dropavator
Every dropper is comparator tested and clocked dropper tower, but the circuits wraps completely around the dropper tower. This would make make any sort of mid-level item feed a practical impossibility, unless you stagger the towers with hopper pipes. Some special circuit modifications is even needed to simply allow you to add the input hopper pipe.
Alternating Side-to-side Comparator Tested & Clocked Tower
-
(9x2 variant) (7x3 variant) - (another 7x3 variant, note the half slab)
Basically as comparators can not 'stack' you must place comparators on two different alternating sides of the dropper tower, to avoid problems. There are many variants, just as there is many dropper clocking methods.
The two designs are ones I came up with but both are obvious, I would not really put my name to them. Though there are as many variants as there are dropper clocks. Interaction effects means the clocking repeater must be set at 2-ticks, to prevent an irregular flow of items (see discussion above).
Timing tests using a 16 high tower timing the delivery of a hopper feed stack of 64 items, with top most dropper feeding a chest at the very top of the tower. 1 tick delay on repeater: 75 seconds. 2 tick delay on repeater: 48 seconds. (See post 34 of this topic)
Alternating Side-to-side Comparator Tested, using Fast but Seperate Clocks
(the tower) (the clock, extra delay on first repeater)
This uses the output of the testing comparator to run a seperate fast comparitor clock. It is one of the standard types of dropper clocks, which is typically used run a dropper a higher speed than then normal comparator-repeater clocks. Typically fast enough to allow the dropper to handle items from two hopper pipelines feeding it. Though of course a single destination hopper pipeline would not be able to accept such high rate of item flow.
Unfortunately this clock is also known to generate extra click when the last item in the dropper has been sent. That extra click is caused by delays in the circuit and the very high speed of the separate clock. As a a single hopper pipeline can not feed such a dropper tower fast enough, that 'empty' state would be reached quite regularly. As a result thsi tower clicks fairly randomly while also causing item delivery to be in spurts of roughly 4 items at a time.
Even with the irregular delivery, this tower is much faster that previous ones. Timing tests show that it can deliver a hopper feed stack of 64 itmes to the a chest at the top of a 16 high tower in a average of 35 seconds (Using the tower pictured).
As the input is slowed by the single hopper feed, placing a stack of items directly in the lowest hopper, delivered those items to the top chest in just 23 seconds, though arrival was still fairly irregular, and it still clicks at the end, though not in the middle of the run. That means placing a second hopper feed below the testing comparator for the second dropper would be a practical improvement.
Actually this design is pretty close to TimeOfSouls Max Speed Dropper Tower. The only difference is that his design is a Stacked Mini-Tower Design, that uses the fast comparitor clock to run 3 droppers at a time instead of just one, and all the clocks are on one side. The redstone is also more open allowing you to feed two hopper pipes from a double chest, more easilly. As such I refer you to his design for the next stage in the development for a high speed tower design.
AntOfThy's Rear Comparator Tested and Clocked Tower
(front) (circuit 1 above & side) (circuit 2 above & side) (alternative)
A variation I came up with that manages to place all the comparators all on the same side of the droppers, allowing the circuit to shift to the left and right. This make smaller more compact fully tested and clocked tower, using a smaller 6x3 footprint.
The final image shows an alternative for one circuit, making the tower fit in a 5x4 footprint, though the front remains only 3 wide.
Interaction effects will slow the towers item rate to irregular spurts unless you set all repeaters to use a 2 tick delay (see above). Both variants of the tower delivered a stack of 64 items up 16 droppers in 47 seconds. not the fastest, but not slow either.
Fishbone Tower: Fully Tested, Interference Free, Fast and Silent Tower
(the tower) (half slab needed next to hopper inputs)
With the help of M0RT1F3RU5 on this forums, a clock was found that has a 1 tick comparator testing clock but which does not cause interferance between each layer of the dropper clocks. This means a tower clocked using this specific dropper clocking method does not have a slow irregular arrival of items at the top.
Time to deliver 1 stack of 64 items from a hopper feed to a chest 16 block up, 34 seconds. A fast, reliable and above all silent, fully-tested tower.
The name is derived from the fish skeleton look of the tower, especially if you use half slabs for the blocks holding the redstone circuity, instead of full blocks. For more information see post 42 of this topic)
You must use this exact clocking setup without change to get a interference free, and smooth fast delivery of items in a fully-tested tower, as small seemingly inconsequential change can cause the interferance pattern to return. For example, replacing the repeater that powers the block powering the droppers with a slightly faster comparator will cause the interferance to to return.
However replacing the solid block the clocking repeater feeds with redstone dust, does not cause a problem, and doing so will make the tower look even more 'fishbone' like.
WARNING: The speed is fragile, the timing interferance is likely to return in MC v1.8
FarhanTZ's Dropper Tower
Another fully tested tower, using the standard 2 wide clock of most of the designs, but twisting 90 degrees each time. Droppers completely accessible on one side, but its large foot print makes it difficult to build into a larger design.
See also "Multi-tested, Single Clock Designs" (below), that seperates the testing of the droppers from the clocking of the tower.
After failing to find a good "Fully Tested Tower Design", the next method is to simply cycle the tower using a single comparator at the base, and then power all the droppers from that comparator, (or clock). The result is a design that I call a 'hosepipe' design.
The tower is only power cycled once, and only once, for each new item in the detected dropper. But items will always be left permanently in tower. What many people don't realize however is that these items are NOT stuck.
The items will continue to move up the tower, as more items arrive at the base. In other words the items that are left in the tower are just waiting for more items to push them further upward. This is much like water in a garden hose. When you turn on a tap, water will immediately come out, but it is not the same water that just entered the hose.
Is that a bad thing? No. If attached to a mob system, the tower will constantly be flushed by new items, especially useless zombie flesh!
The key reason these towers work as they do is that the dropper powering will pulse up the tower much faster that the items themselves move up the tower. That is either a half-slab (or glowstone) power riser is used (instant power), or a single block torch tower is used (two droppers per tick). Either way items only move up a certain distance (typically 2 or 4 droppers) each time the tower is 'pulsed', though the initial number of droppers up to the first 'in-the-pipe' item can be more than this.
A secondary 'flush' clock can added either by having the first comparitor power a clock of some kind. Alternativally by setting the testing comparator to difference mode (light the output torch) and adding a switch on the bottom dropper, or the intervening block. That turns the testing comparator into a 'clock'. Typically it is not needed, unless the player is leaving a site, and really wants all the items 'delivered'. See Over-Clocked Tower Designs below.
Advantages
* Very resource light
* No clicking, except during initial loading of in-pipe items.
* simple design using the right power feeds.
* a small over-clock and/or flush system can be added to clear tower.
Disadvantages
* Always has one item every few droppers in the tower 'in-the-pipe'.
* Can be hard to get that 'special item' out of the tower, unless flushed.
Example Tower Designs...
Simple Hose Pipe Dropper Tower
Very simple circuit, and silent. Just directly power a half-slab redstone riser next to dropper tower from the item detection comparator loop. It fires once every 2 ticks (no delay on 1 tick repeater) for each item in detected dropper, causing items to move up the tower two droppers, about as fast as a single hopper feed.
It does click while items are initially loaded into tower, but then it becomes Perfectly Silent. Continuing the signal higher than 15 blocks becomes problematical, and linkage between stacks of towers may require hoppers to isolate the towers.
This is actually similar to sZPeddy's Item Elevator (see below), but without any over-clocking circuit (I found his design later).
2x1 Compact Dropper Hosepipe Tower
(base circuitry) (power feed) (stacking)
This design is basically a dropper tower with a single block torch tower running up next to it, directly hooked into the comparator clock. No extra clocking is provided, (such as is ACtennisAC tower, below), so items will be left in the dropper tower. But again these are not actually stuck, just waiting.
For this specific varient, the first item is left in the 6th dropper, and then as with all torch tower hose-pipe designs, every 4 droppers after that.
This has to be the smallest, simplest dropper tower you can possibly make. As long as you don't mind a couple of extra clicks at start and end of an item feed, it is actually silent in the middle of an item run.
The torch tower must run on a 3 tick clock cycle (2 on the repeater), it can run faster on a 2 tick cycle, but the torches may burn out occasionally leaving an occasional stuck item, typically in the second dropper from teh bottom.
The design can also be over-clocked (see that section) which helps clear any posible stuck items, and if clocked a lot, clear the 'in-pipe' items, at the end of a run.
For an extra mid-level item feed you can simply break the tower, and add another comparator circuit, so as to 'stack' the tower. The next comparator and feed point must be in the dropper above the final torch in the lower tower. The block above that torch must also be removed, to prevent overlapped dropper powering, and interfering with each other (see images).
As always there are lots of variations in design, but it is so common no-one can really claim ownership, except for a specific variation.
You should also see "AntOfThy's Stacked Tower" variation (below), which while using this type of hose-pipe design, does not leave items in the tower!
Tilable Hose Pipe Dropper Tower
A tilable version of the Hose Pipe Dropper Tower, using a hopper clock (1 item) to drive the tower. The 'in-pipe' items start at the 5th dropper and every 4th dropper after that, and once in place the tower becomes perfectly silent.
This is a highly recommended tower, especially as it is the only tilable dropper tower known. This make it well suited for connection to a bank of item sorters as part of a compact storage system.
However you cannot simply stack the tower (see conditions in the previous tower design) for a mid-level item feed, as the torch tower being 'in-line' with the comparitor will interfer causing power interferance issues and probably timing issues as well. That can be solved only by destroying the 'tilable' feature of the design.
Drakkart's Droppervator Tutorial
This was posted about 20 days after 'host-pipe' descriptions was first published on the MineCraft forums. And to me it shows that the message about 'hose-pipe designs' is getting through. It is a slightly simpler variation, leaving the first item in the 5th dropper (4 droppers up from the comparator tested dropper), and then every 4th dropper from there on.
However the design powers the block that sits between the first dropper and the testing comparator (bottom block for the redstone torch tower). This as mentioned before is not a good idea simply as the comparator can then become powered not from the dropper contents, but from the powered block.
Strangely this does not seem to happen in this case, though I have seen it happen in other designs where that block becomes powered. Why this is case here I am not certain, and to me it is a part of some of the mysterious behaviour I have seen in many redstone designs.
Rather that leaving items in the tower (as in the "Hose-pipe Design"), the tower is over-clocked after the last item leaves the bottom most dropper, until all the droppers are clear of items.
This generally requires some form of extended clocking circuits at the tower base, with the tower power coming from a separate clock to that of the testing comparator.
This over-clocking period tends to produce a lot (and I mean a lot) of extra clicking, especially at the end of a item run. This noise can be very annoying for dropper towers. Especially if they are in your main base.
By using a 'half-slab' power feed with this method you can clock the tower at a very high speed, allowing you to transport items at a maximum possible rate, without redstone torch limitations. As such these tower include 'maximum speed' type dropper towers.
There is also a method of clocking a torch tower at high speed by pistoning a redstone block above a single redstone wire, which results in a phase shift of the pulses and bypassing the games torch burn out code. But I would not rely on it.
Advantages
* Resource light
* larger circuit for clock and detection pulse sustaining
* Can be made to flow items at double the rate of a hoppers
Disadvantages
* Generally LOTS CLICKING from powering empty hoppers (esp. at end)
* may need pistons to rapidly pulse a redstone torch tower
* Items can only be feed at levels where you have a comparator clock
Example Tower Designs...
ACtennisAC 'Easy Item Elevator'
Very simple torch tower. With a long extended over-clocking. This makes it slow to start, and a very long (noisy) over-clocking period at the end of an item run.
The taller teh tower, the longer the over-clocking period, and the more repeaters that is needed. It is not recommended for anything but a very small dropper tower.
MineCrafters987's (Rjblair77) Compact Vertical Item Elevator (with small over-clocking)
Basically a simple compact 'hosepipe' design with a very small (two extra block) clock attached. The Clock is great for small (under 20 block) towers, though as with all overclocked towers does add more noise to the tower.
Mistahtokyo's Hopper Driven Over-clocking (tilable)
http://imgur.com/a/MtSr7
sZPeddy Simple Elevator
Though I would not call it exactly 'simple', the video provides a very clear tutorial. The over-clocking is provided by a 'fade-out' comparator loop. Handles double hopper feeds, but will click a lot on start, end, or with only a single hopper feed. However a fade-out will set a limit on how high the over-clocking will send all items in the tower.
Benonthetubes Fastest Item Elevator?
Using a half-slab power feed (showing how to continue past 15 blocks), this tower uses a extremely large and complex over-clocking system so that it can drive the tower from bedrock to ceiling while running at double hopper speed.
The next style was to slow the power pulse going up the tower so that it travels at the same speed as a single item travelling up the tower.
That is each item is pushed up the tower in sync with a power pulse, that is being sent up the tower.
The item and the power pulse moves together in a sort of wave, that the item rides, like a surfer on a ocean wave. The speed required of about one tick per dropper is quite fast. Though the overall item feed rate can vary with the design, due to clocking method and also perhaps redstone torch limitations. Each dropper (except the bottom feeder dropper) only ever has at most one item, and only for a very brief moment, as the item moves up the tower.
The power pulse typically uses a 2x1 alternating redstone torch tower, which provides the right delay between each dropper, though SabreMage, uses a pure repeater design, which could be used to make the frequence of pulses faster, and thus the towers overall speed. However his design still contains a redstone torch, which limits the item feed rate to the same as torch tower.
The droppers are typically powered by open redstone torches with no block on top, as this cleanly powers the droppers, without power overlaps. These powering torched are connected to the side of the torch tower, making a 4x1 or 3x2 tower size.
However you can also directly power droppers from the torch tower or though repeaters or even direct wire or redstone dots. The 'wave' nature of the power pulse will prevent power interactions within the dropper tower (though not at stacking points). However this method will cause extra clicking, especially at the start and end of a item run, and may make 'stacking' towers much more difficult.
There is a way to set up a 1 tick cycled torch tower without burning out the redstone torches, but that involves the pistoning of a redstone block back and forth over a single redstone wire, making it noisy. It works because the piston generated pulse is a 1/2 tick (1 game tick) out of phase with the normal redstone updates, so by-passes the redstone torch burnout test. This however may get fixed at some point.
Advantages
* Resource light (typically 3 torches per 2 droppers)
* No clicking if done properly
* droppers empty most of the time
* individual items move very very fast to top of the tower.
Disadvantages
* overall item rate is limited by pulse rate, and torch burnout.
* tower can typically only have an even or odd number of droppers, depending on the clocking feed.
Example Tower Designs...
ToastedBaby torch dropper tower elevator
Uses a comparator clock, so multiple items can added at base. Speed is at a 2 to 3 tick rate to avoid torch burn out. It is perfectly silent.
The main tower is 4x1 wide, which allows it to be encased in a 3 block wide wall. or you can twist the torch tower (as in my photos) to produce a 3x2 'L' shape.
However this design needs to be an odd number of droppers high. Also note that the torches are on by default, so you need to be careful of nearby hopper pipes.
When stacking towers (for a mid-level item feed), the top torch on a mini-tower could be under where you add a comparator, or the block between the comparator and the dropper tower. This can cause power interaction issues.
AntOfThy Alternative Design to ToastedBaby's Pulsed Tower
(base circuitry) (power feed up tower)
This design is basically the same torch tower as per ToastedBaby's design, but the base has been redesigned, so that the first dropper is powered from the redstone torch (as a inverter), rather than a direct power feed from the comparitor. As such all the droppers unpowered by default.
The new power arrangement also means the tower is an even number droppers
high, and is now perfectly silent. The power arrangement does not extend
downward below the bottom-most dropper, removing any power interaction issues
and as such you can now 'stack' multiple towers on top of each other.
Unfortunatally the base circuit of the a tower 'stacked' on top will need to be rotated 90 degrees, as the comparator cannot be placed above the top-most redstone torch of the tower below.
Soenderups - Silent Elevator (demonstrated by CubeHamster)
Also uses a redstone torch tower to power a set of torches without blocks above them, so cleanly powers the droppers in pairs.
It is practically identical to the previous design but with an extra column of blocks with redstones dots on them. That column ensures dropper powering torches are off by default, and to me feels like wasted resources.
alfabitslp Compact Minecraft 1.5 Item Elevator
(base circuit) (power feed)
A pulsed torch tower design, but uses repeaters to deliver power to the droppers. However this power arrangements will also power a dropper below the one directly powered, however this dropper is normally still powered by the previous pulse (so no extra click).
An item feed limiter is used to ensure the tower does not generate stuck items due to the power overlaps that exist in the tower, but the result of this is a fairly complex base circuit that makes this design diffcult to install in space limited areas (which is a typical problem).
The power overlap, caused by the use of repeaters, also means you cannot stack these towers to provide a mid-level feed. If you try you will get about 1 stuck item per stack of items, appearing in the second dropper from the bottom of the stacked tower.
On the other hand by using a repeater to power the droppers, the final chest can be placed on a completely open floor at the top. That is something a redstone torch pulsed tower cannot do, without posibly leaving one 'hosepipe' item in the last dropper below that chest, by using a solid 'floor block' above the final torch.
SabreMage - MC-1.5.2 Item Elevator
Small clock, but large (very open) repeater based power feed to delay the pulse up the tower. Redstone powering torches, are placed on alternating sides, which wraps around the droppers on three sides. The glowstone and even support blocks in the design may be replaced by half slabs, to save on resources.
KMBKomhyr - Silent, Fail-Proof, SMP-Friendly Item Elevator
A very novel way of passing the pulse in a spiral up the tower while only powering one dropper each time.
The disadvantage is that droppers become completely wrapped by the redstone, though it does make it quite compact.
Draykke Devry 1.7+ Dropper Elevator
Another simple variation of the pulsed design with variations for odd number of items.
His even number variation however relies on a trap chest to power the last dropper on opening, so does not work for continued item transport. Also the trap chest is likely to cause a item jam if the tower is active at the time you open it.
His use of a repeater to power the base dropper will cause power interferance and thus preventing stacking of towers for multi-level item feeds. Finally his design does not include a clock, so if lowest dropper gets more than one item, say due to a chunk load glitch or multi hopper pipe feeds, it will become locked in a always on state.
AntOfThy Stacking Pulsed Item Dropper Tower
(base) (power & stacking)
This is a design I developed from the previous designs, that specifically allows you to stack a pulsed item dropper tower without power interference. It will stack neatly at intervals of any even number of droppers, and like all good pulsed item designs, is perfectly silent.
Also as the torches are sited to one side of the droppers, the comparitor for the next 'stack' (mid-level item feed) is not located above a redstone torch. This means the stacked towers base circuit does not need to be rotated as it is in ToastedBaby's Pulsed tower design.
These tower designs still run the whole tower using a single clock (so can be noisy), but the clock is only run while items are still in the tower. This is achieved by using comparators to test the tower at multiple points, and then sending that 'detect' signal to activate the clock. The the clock then powers the droppers. Typiclaly the clock is at the base, with the power signal running up the whole tower. the tower could also be run from a switch at the top of the tower.
This means items can be feed into the tower at multiple points, not just at the bottom, and the tower will detect them and clock the tower.
In one sense these are a sort of "Over-Clocked Tower Design", but without using a 'fixed' run time delay on the clock. This means the time the clock runs will automatically adjust to the size of your tower. As such it you want to make it taller, you can just do so, and it adjusts the run time accordingly.
In another sense these towers are just one step away from being a "Stacked Dropper Tower Design" (see next), and thus noise.
Of course this means the tower is not quite as compact as the last few design types, but certainly not as heavy on resources, or use as many supporting blocks as Fully-Tested Dropper Towers does.
Advantages
* Medium use of Resources
* Items can be feed an multiple points
* Timing automatically adjusts to tower height
* Clock only runs while items in tower
* More open circuit compared to normal fully-tested towers.
Disadvantages
* Generally Noisy, especially if items are being feed high the tower.
* Items can only be feed at levels where you have a comparator clock
* Clock can stop/start as the last item reaches the top of the tower.
Example Tower Designs...
Whezolor Fully Tested, Single clock, Dropper Tower
This design has a comparator testing every dropper in the tower. These then feed a down signal to run the clock at the base of the tower, which powers the whole tower. As such no stuck items are possible. In many respects the circuit is fairly complex, especially at the base.
Unfortunately this means the tower has a large footprint all the way from top to bottom.
mrvdg (Merv Dog) Multi-Tested Tower
This is a much simpler version of this type of tower, with the main tower occupying a very small 3x2 footprint. It uses a torch tower to power the droppers, but also tests the specific spots (every 4 droppers) where items can be left behind to check if the tower is clear of items. That signal is then sent down the tower to run the clock.
This makes the design very simple by comparison to Whezolor's, and actually even pre-dates Whezolor's more complex fully-tested design by a month or so. Kudo's to Merv Dog.
The clock at the base is quite simple, but I think could be compacted a little more by using a 1-wide vertical clock, rather than a flat 'ground' clock. But that is just packing.
These are designs that actually rely on stacking smaller towers of more than one dropper, to achieve some purpose. This is typically used to ensure the tower is completely cleared of items, but the stacking can also be used to reduce over-clocking times (if any), and thus the amount of empty dropper clicking (noise) that most designs above generate.
The biggest advantage of using stacked towers is that you can feed items at many levels up the tower. However you may still need to watchout for "Item Jams", that can result from a mid-level item feed. Because of this a design that self-clears has a added advantage.
Advantages
* medium resource requirements
* no items left in tower (generally)
* multiple points for an mid-level item feeds
* great if the stacking corresponds to you build's floor levels
* Only a few clicks, if any, in each mini-tower, for each item run
Disadvantages
* may not be perfectly silent, (but low noise)
* Item feeds only at specific points.
* may item jam on heavy mid-level item feeds.
Example Tower Designs...
purpledragonnuke Duluxe Storage Silo Dropper Tower
Note the video only shows the tower as part of a larger build of a storage silo. Jump to 7:10 to see the 'droppervator' details.
This tower is different in that it actually relies on quasi-connectivity to convert a single dropper powering method into a 2 dropper powering method, allowing it to stack every two levels. It is not really light on the redstone, but is still a lot smaller than a Fully-Tested Dropper Tower. As it does not use redstone torches, it can use, and probably relies on a faster clocking speed. Timing measurments still to come.
In towers with a even number of droppers, a item will be left in the last dropper, but it isn't stuck, and will be replaced by the next item that comes up the tower. For odd numbered towers, slightly different circuit at the top, will not leave any items in the tower.
It is completely silent in the middle of a item run, but does tick a little at the start and end of a run due to overlapping powering. For the same reason, I would not recommend directly stacking this tower with any other tower design.
timeofsouls Max Speed Dropper Tower Returns!
This design uses stacked 'mini-towers' each 3 droppers high. A very small over-clocking circuit is attached to the normal comparator test. That way the tower is pulsed one extra time at the end of the item feed, which keeps each mini-tower clear of stuck items, while avoiding linkage problems when they are stacked.
The circuit is very small relative to other over-clocked designs, but as mentioned is repeated every three levels so is more resource heavy and volume heavy than other over-clocked towers. But it is much lighter than other designs with comparators on every level or every second level, and clocking circuits are easy to get to for adjustments. Especially in survival minecraft.
It is also very fast and as such needs a double hopper feed to keep it working at peak performance. With such a feed it will run silently, with clicks at the start and end of a large item run.
The screenshots shown are slightly more compact alternative circuit layouts. It is still the same circuit, but with the secondary comparator clock flipped to reduce its footprint slightly (4x3 area).
In one variation to the design to extend the half-slab power feed to make each mini-tower slightly taller. You will then need to also extend the clocking, and thus the increase the amount of clicking noise at the start and end of a run. That extendability can be important for towers that are not a multiple of 3, or you need hopper inputs at a different level. Just watchout for power overlaps between tower stacks.
AntOfThy, Stacked Hosepipe Tower
(base) (stacking) (overview)
This is another variation of the "2x1 dropper hosepipe design". With a slightly more compact clocking and power feed into the redstone torch relay tower. Each mini-tower is 6 droppers tall which is a good multi-floor spacing.
The key to the design is noting that the first item that remains in the 'hostpipe' design is 6 droppers up. At that point the tower is stacked meaning the item will now be immediately detected and sent further up the tower by the next comparator clocked 'mini-tower'.
In other words this is a 'hosepipe' design that is stacked in such a way as to leave no items in the tower. Thus is no longer a hose-pipe design.
Yes there is some clicking at the start and end of item runs but it is very light by comparison to over-clocked designs. Also 'stuck' or 'jammed' items will in most cases slowly self-clear the mini-tower with time, just as they do in the normal "2x1 hose-pipe design".
The clocking circuit shown above also has a slightly smaller footprint, but at a cost of extra depth to the clocking circuit.
Final notes and Recommendations
My suggestions... depends on your needs...
My recommended designs (developed from this extensive study)...
Tilable Hose Pipe Dropper Tower
A simple tilable hosepipe tower, though needs 2 hoppers. It is silent but has a cost of leaving one item 'in-the-pipe' at the 5th dropper and every 4th dropper after that. However you cannot stack two of these towers directly on top of each other.
If space is not an issue or you need mid-level item feeds, look at the next recommendation.
AntOfThy's Stacked Hosepipe Tower Design
(base) (stacking) (overview)
Though this tower is not silent, it is not overly noisy either. It can be stacked, and if stacked at a 6 droppers no 'in-the-pipe' items will be left in the tower.
This tower will very slowly 'self-clear' "Item Jams" by one item at end of each item run. That is the cost of the extra click!
AntOfThy's Pulsed Item Stacked Tower Design
(base) (power & stacking)
This tower is perfectly silent, and will stack at any even number of droppers, and as with other pulse-wave designs does nto leave items in the tower.
The cost of this is that it will not self-clear "Item Jams" caused by backflows, or vertical chunk load issues. They will simply 'remain' until manually cleared.
test137E29's piston-less glass item elevator
This is a game changer for item elevators. No pistons, no redstone, and with packed ice, no light-ice problems, no noise, very cheap, and looks so cool too. This elevator is probably the better solution for any situation involving large numbers of items, or for moving items up more than 20 blocks, even if it means having a dropper (or two) feeding the items being transported into a water stream.
The same video also illustrates designs for "instant dropper towers and pipelines" however while these are 'instant' they are so heavy on resources, especially gold rails, and such not practical until you have a gold farm. I doubt many players would want to use them. Still it is available, and who knows, may be usable as a multiplexed instant signalling method.
Signed AntOfThy, Last update 26 June 2014, MC v1.7.9
First... you just posted your design without even reading the original post!
And yes your tower works. It is actually almost identical to ACtennisAC's design. It is mostly a 'pulse dropper tower' but with a small over clock to handle any stuck items.
But I very much doubt you can 'stack' two of these to add a extra feed in the middle! At least not without a lot of effort.
Note a torch tower like this clocks three droppers on every torch. WIthout the over-clocking (which produces that final click) the arrangement of power handling will generate a stuck item. On other other hand side mounted set of torches (no blocks above the torches) will smoothly and cleanly power only two droppers per pulse. That is a single item move up two droppers on each pulse (reason why some designs can handle a double hopper feed).
Now you mention in the video you can build it up higher.. Have you tried? I doubt with the amount of extra over clocking provided, you would get all the itmes to the top of a 100 block high tower. But then would you want to.
I suggest you figure out how to 'stack' two of these on top of each other.
In summery: it is likely to be a good reliable design that works. But you probably can not directly stack two of them without a hopper, to isolate the power handling. And it clicks.
Single torch tower powered dropper tower would actually make a good 'Hose Pipe' design. That is some items always remain in the tower, but will move upward as more items enter at the bottom.
PS: I have a personal preference to avoid a tower with any sort of clicking, it speaks to the engineering part of me of in-efficency in design. Though I understand they work and include them in my study. I also like adding a lamp every block (off when not in use) to show when the the tower is running. :-)
After some testing of a single block torch tower next to a dropper tower (such as in Rjblair77's) reply...
Yes the redstone signal out paces the items in the tower. However because an item moves two droppers ech time a torch powers on, and each torch is alternative on/off up the tower, a full pulse (on then off) will move items upward four droppers at a time.
That does make a great 'hose pipe' design, even without over-clocking.
Imgur album link (two images): http://imgur.com/a/MtSr7
The single torch method of distribution can be changed, but is our personal favorite because it is compact and doesn't burn out with the hopper clock. We've used several of these in our server's iron farm and after filling 18 double chests with iron ingots, there are still no issues whatsoever. Multiple feeds can be managed, but would require some editing that I'm too lazy to provide at the moment.
It is a nice design, an essentially the same as the just added 'Compact Dropper Hosepipe Tower'. Just with a more complex hopper clock to do the timings and to create 1 extra pulse on the end. Much like Rjblair77's Tower Design has a extra clock (over-clocks a little longer)
As you mentioned this type of power feed system will leave 1 item for every four droppers (not stuck, just in the 'pipe'). You should have 2 items in this tower, but over-clock the tower by one more pulse. If you extend your tower up higher you will have more items left in the tower 'pipe'. It also 'clicks' even in the middle of an item run, though in this case the extra clicks slowly 'self flushes' any extra stray items.
A big advantage I see for having a separate clock, is that you can add a lever (or even a button) on the block the comparator points to. When you activate it (for a short time) the items in the tower will then be flushed out. Useful if you want to push all items up to a mine cart when leaving the area for a while.
Being tileable is another advantage, and kudo's to you.
Again you may like to look at how to 'stack' your towers, so as to provide multi-level item feeds, such that does not cause a item jam around the feed. Especially irregular feeds that are hard to test without a couple of mob systems nearby. That is my next line of inquiry with this type of tower.
(a number of designs are really stacked mini-towers).
However if you ensure that the powering droppers do not overlap there should not be a problem. (see original Post).
I will look at stacking towers of this sort and if I get it working I'll post a image of the stacking point. It is likely you will only be able to stack at either an odd, or an even number of droppers, without needing a isolating 'hopper linked staggered tower' stacking method.
I also have to get a photo of the stacking (even number of droppers) for the Pulsed Tower Design I now use.
The key was to place the mid-level feed on the level one block above a restone torch.
BUT remove the block above that torch so it does not feed power into the upper mini-tower.
Here is the working solution, the third image is the stacked tower power feed.
http://imgur.com/a/XIm6J#6 (base circuitry)
http://imgur.com/a/XIm6J#7 (power feed up tower)
http://imgur.com/a/XIm6J#8 (stacking towers)
Now the only way I locked this up was to add many stacks of many different items directly into the mid-level feed dropper. When that happens items in the dropper below may become 'clogged' and stuck. however for a single hopper feed at the mid-level this is not going course this to happen very easily (hoppers only can hold 5 different items, droppers 9 different items and randomly send items up)
But that is a problem for any stacked tower.
The problem is made worse by the fact that droppers and hoppers always stick items in either the first available free slot, even if there is a incomplete stack of the same item somewhere else in the container. that is they can fill multiple slots with the same item.
Note this does not happen when users 'shift-click' items into such containers, only with hopper or dropper feeds into the containers. I consider this to be a bug.
KMBKomhyr - Silent, Fail-Proof, SMP-Friendly Item Elevator
A very novel way of passing the pulse in a spirl up the tower while
only powering one dropper each time.
Design may be improved by replacing the 'hopper' clock (which clocks at
half the hopper speed) with a 1 tick comparator clock.
The other links are mostly youtube video links, and youtube does not provide a nice thumbnailing method.
UPDATE: I also rebuilt almost all towers on the CubeKrowd server, so people can go take a look. Also more screen shots, and of the various towers and their respective parts.
That is tower designs that actually relies on regular 'stacking' of the towers.
Currently two designs stacked every 3 (timeofsouls) and 6 (antofthy) blocks.
More images of the various types of dropper towers, methods of powering, and a starting image of what I consider one of the best (not overly complex) designs so far to come from this study.
I hope this helps improve responses, as this is an area that can use more attention, considering just how useful dropper towers are.
So make use of it. And letting me know what you think. And above all, some credit for the work I did would be nice. ;-)
Note that I have rebuilt practically all the Dropper Towers on my
creative plot on the CubeKrowd MineCraft FanServer... cube.jl2579.net
login to the server, type /cr, and then /tp -4900 30 -6000 (you are in creative do don't worry about falling).
But again, we are currently upgrading the server to make it work better, so it may be a couple days before it is available to work on, and there may be a need to move your build to the new creative world as I believe the chunks of the world you built in had some weird corruption issues.