I'm using a Raspberry Pi 3B.

What is the easiest way to make and break a single connection under program control - just like touching two wires together?

  • 2
    you can short anything to anything else to close a circuit ... the big question is what are you trying to do?
    – jsotola
    Jul 18, 2019 at 22:24
  • 1
    Just to be clear, I think foxrider's suggestion above is incorrect and could result in you cooking your Pi. Or it might work, but without further information you can't know.
    – Mark Smith
    Jul 19, 2019 at 20:54
  • 1
    That comment (now deleted) seemed to imply a GPIO set high could be connected directly to ground without frying the Pi, which is false.
    – goldilocks
    Jul 30, 2019 at 13:28

1 Answer 1


Buy a cheap relay from Amazon (like this one: Amazon GBP7 for five units) and use this to switch your signal. Don't try to connect your circuit directly to GPIO without a relay.

  • Hi Jonathan,description of your relay is 10+ years out of date. It mentions PIC, AVR, DSP, Arduino, but how come most popular Rpi is not mentioned? I know PIC and Arduino are MCUs. But are AVR and DSP MCU or SBC? I have the feeling that the Amazon UK guys do not speak English and do not know Raspberry Pi. - ARCELI 5PCS KY-019 5V One Channel Relay Module Board Shield For PIC AVR DSP ARM for arduino Relay by ICQUANZX ( amazon.co.uk/ARCELI-KY-019-Channel-Module-arduino/dp/B07BVXT1ZK/… )
    – tlfong01
    Jul 20, 2019 at 0:46
  • Sorry for the delay replying. The 5V relay shown works fine with the Pi - I have done this many times.
    – Jonathan
    Jul 30, 2019 at 10:41
  • 1
    Hi @Jonathan, No worries. I have been using the relay you are recommending for over a year, and so far so good: RE: RELAY MODULE KY-019 5V Postby tlfong01 » 2018-Jun-02 Sat 10:10 pm raspberrypi.org/forums/viewtopic.php?f=37&t=77158#p1323061, What I found surprising is that Amazon UK speaks broken English, and doesn't even mention that their KY019 relay is Rpi compatible, otherwise their sales should at least double by now.
    – tlfong01
    Jul 31, 2019 at 2:50
  • 1
    Yes, Amazon is selling millions of things, so no time to pay attention to each of them. BTW, I found Hobby Electronics RALAY5VM description very good. (1) hobbytronics.co.uk/5v-relay-module?keyword=relay, (2) hobbytronics.co.uk/about-us.
    – tlfong01
    Aug 10, 2019 at 8:53
  • 1
    My pleasure. BTW, though those York guys at Hobbyist Electronics don't speak Oxford or BBC English, their technical presentation is professional and at the same time hobbyist and newbie friendly.
    – tlfong01
    Aug 17, 2019 at 1:05

Not the answer you're looking for? Browse other questions tagged or ask your own question.