Connecting two DC power sources to switch by ground

[bhollehday]

Im trying to use one end point switch to drive two seperate DC sources. One is a 24V dc power supply ground hooked up and I want to use that ground wire to trigger a controller that is powered from a completely seperate dc power source. Is this bad practice or will it work? Can I connect both ground wires from each source to the same switch without issues?

 

[Pommie]

If in doubt, use a dpdt switch.

Mike.

 

[bhollehday]

If in doubt, use a dpdt switch.

Mike.

Problem is the switch is specifically mounted and it will be a problem to replace it with a dpdt.

 

[gophert]

Define "trigger".

I am confused. Do you mean:
A) the controller is continually powered and it needs to sense/count/do something every time the 24v circuit powers up?
Or,
B) do you want the powering up of the 24v circuit to power the lower voltage controller circuit
Or
C) do you want the powering up of the 24v circuit to somehow "enable" a separately (yet continually) powered controller.

 

[bhollehday]

I want the 24v volt to send a ground signal to the controller when the switch is activated. The controller has a ground input so I’m guessing that ground needs to be the same grounds as the inputs being triggered.

 

[gophert]

I think this should do it.

The solenoid is Essentially a pull-up resistor for the switch.

You need to make sure your 12v controller can accommodate a 24v signal.

Also, I don't see a +12v to power your controller in the schematic.