Polarized Capacitor in Reverse Direction


Joined Dec 6, 2017
First suppose that both capacitors are discharged.

In the positive cycle we have :
D1(first diode from left)=off, D2(second diode from left)=on
therefore both capacitors are in back-to-back position and C2(the output cap) prevent a large DC current to flow through
C1. As a consequence, C2 prevents C1 from damage!
Anyway, in the positive cycle, C1 is charged to a voltage equal to the peak of the input voltage (Vm) (transformer secondary voltage peak).

in the negative cycle we have:
D1=on , D2=off
in this cycle C1 is charged to a voltage equal to Vm.

now, in the next positive cycle ( when D1=off and D2=on) C2 receive a charging voltage equal to 2Vm from secondary of transformer and C1.

now you have an output DC voltage which is equal to twice of the transformer output voltage peak.

good luck