I am trying to build a bench digital volt meter using the ICL7107 it needs to be powered from a dual power supply.

I have attached the circuit diagram I tried to follow and build. the 7905 regulator gets hot and I don't know where I am going wrong.

Thanks

Rodney

 

You did not connect the CT of the transformer to the "common" terminals of the regulators. E

 

Sorry I am lost what is the CT (centre tap?)

 

Yes, center tap. Connect a wire from the connection between C1 and C2 to the grounds of your two voltage regulators.

 

Thank you for all the help, I also had made a mistake on my PCB layout assuming that the Pin outs were the same as the positive voltage regulator.

Best wishes

Rodney

 

I also had made a mistake on my PCB layout assuming that the Pin outs were the same as the positive voltage regulator.

You are not the first Electronics are attention to details. Never ever assume anything. It will less than 1% chance that you will be correct in my experience