I'd like to use a comparator to act when e.g. a testforblock command block attached to a button triggers. But the comparator changes its state only when the button is pressed after the test result changes, while I'd like to have a short pulse if nothing changed, i.e.

previous command block state | new command block state | desired output
           on                |           off           |      off
           off               |           on            |      on
           on                |           on            |      briefly off, then on
           off               |           off           |      briefly on, then off

How can this be achieved?

  • 1
    You're committing the cardinal sin of mixing command blocks and redstone. I'm sure there's a better approach.
    – MBraedley
    Mar 5, 2016 at 21:07

3 Answers 3


Try this contraption:

Please accept this answer if you want to.

It will work exactly as you described.


Instead of making a machine, just set up another command block coming out of the comparator with this command:

/blockdata <Insert Coords> {SuccessCount:0}

In my case it is actually sufficient that an on-signal is reset after a short while, which can be simply achieved by splitting the input signal and additionally feeding it to the comparator's side.

  • @QbsidianH20 Originally I intended to test the other answers first, but I never came around to do so, so I guess your suggestion is appropriate...
    – Zommuter
    Mar 6, 2016 at 18:33

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