Here's a minecraft 1.12.2 mod that lets you record when blocks are powered with gametick accuracy. The idea is that it can be a useful debugging and design tool for redstone contraptions. The mod lets you place virtual "meters" in the world which record the power level of a block for the last 60 game ticks. This information is displayed using a simple GUI and can be paused for careful inspection.
Here's a link to a short video explaining the mod and showing some examples of how to use it: