Sometime back we (me and several Pinside members) built a power supply for testing MPUs.

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Inside the box are two separate power supplies – one for 12 and 5 volts and one for 24 volts.

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Each section has its own transformer, wiring, fuse, and on/off switch. I only use the 24 volt section for checking zero crossing and seldom use it. Normally when I use the power supply I connect ground to TP4, 5 volts to TP5, and 12 volts to TP2. When I use the 24 volt section I also connect ground to TP4, and 24 volts to TP3. Therefore I have two test leads connected to TP4.

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What would happen if I connect both ground wires together at the power supply?

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Would the ground wire have any effect when using only the 5 & 12 volt section?

I may win the dumbest question award but I don’t want to harm my power supply.

Thanks
Bob

Thank you all for your input.

I read a few articles about tying grounds together but nothing pertaining to my situation. I didn't want to put the switch in because I didn't want to open the case.

This is what I came up with. It seems to work fine. I booted without the 24 volts - then with the 24 volts. Works just like before.

Again, thank you all.

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