I have a problem and Im not sure what the best way is to address this. I converted an ATX PC power supply to use as a lab power supply I installed a digital volt meter and a digital ammeter. To power my meters I am routing a 12v wire and ground to my meters. I am also measuring my voltage and amps ( on the same power) with these meters. it works fine for the volt meter however my ammeter will not function properly this way. if I hook up my ammeter to a 12v battery then measure the current from my power supply it works but I dont want to hook up my ammeter to a separate power supply to use it. how can I isolate the 12v power to my ammeter to run the meter? I was thinking a 1:1 transformer but this is DC to DC so that may not work. maybe an optocoupler?
Best Answer
You need a "floating" power supply:
Could be a mains powered wall-wart or similar. Cheap and easy and connect and go.
Could use an isolated switching power supply powered from any of the AT supplies. This could be an inductor based design or a switched capacitor design as was discussed here recently. Be sure that the isolation provided meets your safety needs for both equipment and people.