How do I connect this PWM-controlled supply board properly?

[Demon]

Nope, not connected together. No BEEP on DMM.

I have no idea what "galvanically connected" means.


But I did find 2 of the circuits on Proto Supplies:






One connection is GND earth, the other is GND power...?


Proto doesn't have the FR-120N, but I have found a picture of all 3 circuits elsewhere. They seem identical on the top except for the MOSFET used (2 share the same opto-coupler).




EDIT: The PWM comes from a PIC. The PIC and this board both will run on the same 5V supply.

I've just very rarely dealt with a earth GND before.