I need help with this homework question I have trouble solving it. the thing I don't understand is that when the voltage is positive the only diodes that are active are D1 and D3 and I'm not able to see how it happens. I tried to re-draw the circuit with the grounds connected cause it might make it more clear and I also didn't know how to do it successfully.

I'd like to get help and understand how on the positive voltage only D1 and D3 are active.

Thank you enter image description here

  • \$\begingroup\$ When D1 is active, D2 is active as well, not D3. When the input connected to the right corner of the diamond is positive, and the input connected to the left corner is negative, current flows from the upper supply terminal to the left and returns to the lower supply terminal (So D1 and D2). When the input at the right is negative, then you have D4 and D3 active working the same way as I said before \$\endgroup\$
    – Bouboubi
    Commented Oct 18, 2023 at 15:03

1 Answer 1


When referenced to ground, when one side of the transformer goes positive D1 conducts. The other sideof the transformer will be negative and D2 will conduct for that. The red trace shows the path for the positive side of the supply, blue for the negative.

enter image description here

When the transformer voltage reverses D3 will conduct for the positive and D4 for the negative.

enter image description here

This is basically like taking two full wave rectifiers:


simulate this circuit – Schematic created using CircuitLab

And running them both off of the same transformer.


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