While experimenting with redstone, I seem to have come across this strange piston-based circuit:

Although it may not be obvious from the picture, this circuit causes the upper wire to rapidly turn on and off. There is also a block attached to the sticky piston.

How does this work?

  • Doesn't work here.
    – BlaXpirit
    Aug 14, 2012 at 6:45
  • 2
    How is that piston being powered? Aug 14, 2012 at 6:53
  • @SevenSidedDie that is the question Aug 14, 2012 at 7:05
  • @BlaXpirit make sure you build it one block deep. I will add another picture on how to build it. Aug 14, 2012 at 7:06
  • @JoethePerson Oh, I got it. Will write a correct answer now :P
    – BlaXpirit
    Aug 14, 2012 at 7:10

1 Answer 1



When the piston is not extended, the wire is cut and goes straight to the block beside the piston, thus powering it. So the piston extends...


And the two wires get connected, so the wire no longer goes to the block, and the piston is not powered anymore, so it retracts.

The cycle repeats, making a pulser.

The concept of "blocks being powered" is quite slippery unless you fully understand it. This great video really helped me complete my understanding of it.

There is also another strange thing. It is possible to stop the pulser by putting another block near the moving one and then removing it. Even though that block is powered, the piston is not extended. However, when you cause a redstone update (by placing/removing a block or changing a redstone current) near it, it starts going again. This concept is used in Piston-based BUD Switches.

  • 2
    Oh my god it also changed wool into dirt! Amazing! Jun 17, 2013 at 11:36
  • @MarcoGeertsma No, I put that wool to indicate a powered block :|
    – BlaXpirit
    Jun 17, 2013 at 11:37
  • i was joking ofc ;) Jun 17, 2013 at 11:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .