I made a system for moving items into minecarts and back with hoppers, but then I decided it was only mediocre, so I went for an auto reset. I don't know if this has already been done, but I made it myself, and I only vaguely understand how it works.
When the cart first arrives, it sends a pulse to a bunch of different mechanisms. It activates a pulse that goes into a single output, so that a solid current moves through it. A repeater and a piston are built into the pulser so that it can be shorted out. When the current stops, it activates a second piston, that, with the first one, sends the minecart off. It also gives a short delay to the piston in the pulser so it gets cut off and resets. The only error I've come across so far is that if there isnt anything inside the cart, none of the redstone will activate and it will no be sent back.
The map can be downloaded here. If that doesn't work please say so. I can't fix it if I don't know.
When the cart first arrives, it sends a pulse to a bunch of different mechanisms. It activates a pulse that goes into a single output, so that a solid current moves through it. A repeater and a piston are built into the pulser so that it can be shorted out. When the current stops, it activates a second piston, that, with the first one, sends the minecart off. It also gives a short delay to the piston in the pulser so it gets cut off and resets. The only error I've come across so far is that if there isnt anything inside the cart, none of the redstone will activate and it will no be sent back.
The map can be downloaded here. If that doesn't work please say so. I can't fix it if I don't know.