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 '12 at 6:45
  • 2
    How is that piston being powered? – SevenSidedDie Aug 14 '12 at 6:53
  • @SevenSidedDie that is the question – Joe the Person Aug 14 '12 at 7:05
  • @BlaXpirit make sure you build it one block deep. I will add another picture on how to build it. – Joe the Person Aug 14 '12 at 7:06
  • @JoethePerson Oh, I got it. Will write a correct answer now :P – BlaXpirit Aug 14 '12 at 7:10


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! – Marco Geertsma Jun 17 '13 at 11:36
  • @MarcoGeertsma No, I put that wool to indicate a powered block :| – BlaXpirit Jun 17 '13 at 11:37
  • i was joking ofc ;) – Marco Geertsma Jun 17 '13 at 11:46

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