12v switch/ button that trips back to the off position upon losing power

I need a DC switch/button that I can toggle on and off, but also when it loses power through it, trips back the off position, if that makes sense. If such a thing doesn’t exist, do there any kind of circuit I can make up.

1 Like

If you google ‘Magnetically controlled toggle switch’ or similar you will get results for the device you are looking for. For instance:
ET Series Magnetically Held Toggle Switches Operation and Electrical Ratings (mouser.com)


Hi Nathan
I dare say you could do this electronically and use a relay to do the actual power switching. I am assuming you want to switch power here. You have not parted with that bit of info. You could have a push button for push on push off function and reverts to off on power loss. From memory I think a 4013 is useful for this sort of thing. Need all the info for anything definite.
Cheers Bob

1 Like

Agree with Bob

@Nathan129552 it sounds like a great application of relay logic for a latching relay. These examples show a SPDT relay, but you can expand to a DPDT relay which will give you a whole extra pole to drive any loads off, keeping the load current away from the switches.

One momentary button turns the system on
one momentary button turns the system off

And if power is lost, the default state is always off.

There are other ways to do this of course eg. Integrated circuits and latching, or microcontrollers. But a latching relay is a very simple and robust solution.


Hi All
The push buttons can be on the negative or Ground side if more convenient.

If you need a single button there will be electronics (IC) involved.
Cheers Bob


The relay solution will not reset a toggle switch or a push/push button switch. The example referenced above is a toggle switch solution that resets the switch. It uses a simple electromagnet with no electronics.

Hi Jeff.
The examples you linked seem very good. However I looked at a couple of devices (2) and got a bit frightened off by the price (unless it was a mistake). The ones I looked at were north of $1000 so I did not look further.
The relay solutions above use one NO button and 1 NC button.
The only comment about Michael’s post is the text says SPDT and DPDT relays but only single throw (SPST, DPST) relays are required for this particular function. Double throw will do the job however if the only one available.
Cheers Bob

1 Like

It’s likely to be expensive but careful searching might throw up something suitable. OP is asking if such things exist, and they do. The relay solution will not trip the switch back to the off position, and a solution that does trip the switch does not rely on electronics.

1 Like