solidago
Posts: 1
Joined: Wed Sep 13, 2017 6:49 pm

Monitoring a 12v circuit

Wed Sep 13, 2017 7:01 pm

Essentially I need a Pi to monitor a 12v circuit. I want to Pi to know when a circuit switch has been closed. When that happens the Pi will take some action.

Clearly I cannot connect the Pi directly to the 12v circuit and I need to place something in between. My knowledge of the hardware options is very limited and am hoping for some advice

Thanks

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KLL
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Location: thailand
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Re: Monitoring a 12v circuit

Thu Sep 14, 2017 1:23 am

to keep the circuits isolated can use a 12VDC relay in the 12VDC circuit.
the ( potential free ) contacts of the relay you can use / connect like a push button
follow the manuals about reading a GPIO connected push button.

drgeoff
Posts: 7220
Joined: Wed Jan 25, 2012 6:39 pm

Re: Monitoring a 12v circuit

Thu Sep 14, 2017 7:23 am

Or an opto-isolator plus a couple of resistors.

pcmanbob
Posts: 1605
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Monitoring a 12v circuit

Thu Sep 14, 2017 9:31 am

Drew this up for some one on here a while ago.

Image

just to be clear the ground under the 12v is the ground for the 12v circuit not the pi.

you can simply leave the switch shown out of the circuit for you circuit.
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