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I need to order a switch to turn ON or OFF a circuit, which would be mounted on a PCB after the power supply. This switch has to meet various specifications (through hole right angle, i>1A, v>28V)

But most of them are out of order on manufacturers website, but I find plenty of ON-ON switches.

Is it possible to use an ON-ON switch with one pin grounded instead of the ON-OFF switch ?

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  • \$\begingroup\$ What do you suppose - to short the voltage input to ground as an "off"-state? \$\endgroup\$
    – MrGerber
    Commented Sep 4 at 12:19
  • \$\begingroup\$ it's really a noob question, but I was wondering if it would be possible to have one "on"-position that supplies the board, and an other "on"-position that has same effect has an "off"-state by connecting it to the circuit ground \$\endgroup\$
    – booo
    Commented Sep 4 at 12:28
  • \$\begingroup\$ I see. That won't work, because then you've shorted out your power supply. It's probably not very happy about it. But as given in the answer, you can just not connect anything to it instead! \$\endgroup\$
    – MrGerber
    Commented Sep 4 at 12:32

1 Answer 1

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An ordinary ON-OFF switch (known as a single-pole single-throw, or SPST) has two terminals. Call them A and B. In one position A is connected to B; in the other position there's no connection between A and B.

An ON-ON switch (known as a single-pole double-throw, or SPDT) has three terminals. Call them A, B, and C. In one position A is connected to B and there is no connection to C. In the other position A is connected to C and there is no connection to B. So ignore C: in one position, A is connected to B; in the other position there's no connection between A and B. Just like the SPST. So, yes, you can use it instead. Don't connect anything to C.

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  • \$\begingroup\$ I would add that it may be necessary to insulate or isolate C in some way. Whatever voltage B has on it, that will be exposed on C. \$\endgroup\$
    – jfowkes
    Commented Sep 5 at 9:16

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