I have torn apart a toy prank electric buzzer that delivers a shock when you press the button. I would like to find a way to send a signal from a GPIO pin to act as the button press. I would then like to encorporate 4 total GPIO pins in this manner that represent players in a game.

The players would each be holding tin foil and I'd like to randomly shock 1 of the players, using just the one electric buzzer circuit, and the GPIO pin representing that player would send a signal and send the shock to just that person.

I am unsure how to wire up a circuit in this manner, so that depending on what GPIO pin sends a signal, just the 1 correct person gets the shock.

I am using the 4V battery source the buzzer originally used (although open to suggestions about using the pi power rails, that won't kill me!)

Here is a lame circuit I made as a starting point. It shows the switch, but I'd like to use the GPIO pins to bypass that.


And here is the circuit so far taken from the buzzer (there was a small circuit board with it that I think had a resistor in it, I'm concerned that not using that I am putting way too much current through the 2 shock wires!)


Thank you!

  • +1 For brightening my day with "I have torn apart a toy prank electric buzzer that delivers a shock when you..."
    – goldilocks
    Oct 18, 2013 at 20:26

1 Answer 1


Use a PNP transistor...

enter image description here

or a transistor array (ULN2003/2803) ...

enter image description here

Just check the datasheet to make sure it can handle the voltages switched.


  • Thank you for the detailed response! So would I provide the charge from the capicitor to Pin 9 on the ULN2003 and say I sent a signal from GPIO to Pin 11, Pin 16 would output the shock voltage coming from the 4V battery/capacitor on Pin 9? And the same for GPIO -> Pin 12 - Pin 15 out? Thus allowing me to have up to 7 players.
    – Titan
    Oct 18, 2013 at 16:20
  • I asked the same question :) That answer is pretty good, replace the motors with your shocker things.
    – Piotr Kula
    Oct 18, 2013 at 19:25
  • PS You need to realise that you might not be able to switch the shocking voltage. How many volts is it supplying to the shock:? 40v?60? maybe more...? If its high voltage it could fry the transistors. You need to swithc the power supply or grounding somehow.
    – Piotr Kula
    Oct 18, 2013 at 19:29
  • oh wow that looks perfect thank you! The batteries provide 4V. My concern was when I pulled apart the device I had some loose cables and a small PCB which I'm presuming had some other components such as a resistor. I haven't used those in my circuit and when I push the button I get 4V discharged from the capacity, but the amps on my meter are off the charts (and I read it's amps not V that can hurt you). I'm not convinced I won't need some form of resistor in the mix too.
    – Titan
    Oct 18, 2013 at 21:00
  • Well, yes. Electricity is generally dangerous. I would recommend you ask that question above on electronics stack exchange. They have some gurus there that will tell you exactly. Please refrain from using that device as it might be harmful
    – Piotr Kula
    Oct 19, 2013 at 8:24

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