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


User avatar
Posts: 987
Joined: Wed Jan 09, 2013 3:05 pm
Location: thailand
Contact: Website

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.

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.

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.


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.
Please only ask questions in the forum I will not answer questions sent to me directly via PM
Remember we want information no help

Return to “Beginners”

Who is online

Users browsing this forum: No registered users and 35 guests