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How to turn an SPST momentary push button into a DPDT? I would like to close 2 circuits at the same time. (From comments: I want to ground the reset circuit while getting a pin to HIGH on an Arduino like board.)

SPST SPST PB

DPDT DPDT

Image source.

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  • \$\begingroup\$ You want the DPDT to also be momentary? Or are you asking, without saying, that you want it to toggle back and forth by remembering its last state? \$\endgroup\$
    – jonk
    Commented Oct 28, 2017 at 22:06
  • \$\begingroup\$ @jonk, I also want it to be momentary. \$\endgroup\$
    – Remi
    Commented Oct 28, 2017 at 22:10
  • \$\begingroup\$ Why can't you buy a DPDT switch? What are you trying to turn on or off? Cant you have the SPST switch simply turn something else on that closes your 2 circuits? This question is too vague. \$\endgroup\$
    – Wesley Lee
    Commented Oct 28, 2017 at 22:10
  • \$\begingroup\$ @WesleyLee Trying to learn alternatives, I'm new and don't have bunch of components laying around + shops are close. how to "simply turn something else on that closes your 2 circuits"? I want to ground the reset circuit while getting a pin to HIGH on an arduino like board \$\endgroup\$
    – Remi
    Commented Oct 28, 2017 at 22:16

3 Answers 3

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Based on the info in your comments. You do not want a DPDT switch, but a resistor and an invertor.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ looks promising. just learned what a 7404 is and your circuit seems to fit my specific needs \$\endgroup\$
    – Remi
    Commented Oct 29, 2017 at 0:21
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schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. Use a relay to provide DPDT action from a single push-to-make pushbutton.

The relay coil voltage should be the same as the supply, V+.

The contacts should be rated for > switching voltage and > switching current. In your case it is small signal so it may be more important to get gold-plated contacts which won't corrode and degrade the small signals.

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  • \$\begingroup\$ That's a good alternative, thanks. I didn't even know there were DPDT relay. But can it also be done with simple components like capacitor or transistor? \$\endgroup\$
    – Remi
    Commented Oct 28, 2017 at 22:32
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    \$\begingroup\$ It depends what you are switching but you have given us no clue about that. Edit your question with the details. \$\endgroup\$
    – Transistor
    Commented Oct 28, 2017 at 22:42
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If you have to keep the existing SPST momentary switch then here is how to convert it to a DPDT switching circuit.

enter image description here

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