Greinacher Circuit Voltage Doublers

I used a 3.3 µF, 370V_AC capacitor in a previous Villard Circuit voltage doubler, but I used 67 nF capacitors in a Greinacher Circuit voltage doubler.

That’s a huge capacitance difference. Did I do the Greinacher Circuit correctly?

Since I did the Villard and Greinacher voltage doublers, my experimentation took a sad turn. I tried polarized electrolytic capacitors in a Villard circuit. Apparently the electrolyte solution boiled. The capacitor burst. Loud bang.

I tried some non-polarized, ceramic disk capacitors, but something went wrong, and the 1N4001 diode in the Villard circuit smoked. Somehow this shorted my doorbell transformer. It quit working.

I got a new doorbell transformer, then smoked a tantalum capacitor.

I finally bought some metallized Polypropylene film 400V capacitors, and some FR207 diodes, which have a 2A forward current capacity.

Doorbell Transformer

I bought an Eplzon brand transformer. According to my multimeter, the 120V side has a resistance of 18.5 Ω. The (nominal) 24V side has a resistance of 1.0 Ω The multimeter consistently measures the stepped down output, which is nominally 24V, at 27.4 V_AC.

Peak-to-trough says 7.6V, but the oscilloscope probe was set to 10x attenuation, so it’s actually 76V. Now that I think about it, is the FR207 diode’s 40V reverse voltage rating good enough? They didn’t even get warm while I was fiddling.

Greinacher Circuit

I used 0.56 μF (rated) capacitors, and FR207 diodes. The breadboard looked like this:

AC comes in from the left on gray wires. DC is on the right, the top orange wire is positive, the bottom, negative.

The output waveform was very boring: a straight line at 74V_DC. This is different than my previous Greinacher circuit, which had 67 nF capacitors, and showed a lot of ripple.

I unplugged the doorbell transformer, but left the oscilloscope on. The straight line gradually decayed from 74V to 0V. I think this is the capacitors discharging through the doorbell transformer and oscilloscope resistance.

I tried other capacitance values. 0.22 μF capacitors produced exactly the same flat 74V.

0.047 μF capacitors gave the DC output a lot of ripple.

This is my whole setup, doorbell transformer on left to oscilloscope on right.