I'm trying to design a high DC voltage generator to create a voltage differential between the upper and the lower part of a cloud chamber I'm building. I'm trying to use a ZVS circuit to amplify an input voltage of 12V and then further amplifying it using a transformer. I'm following the circuit shown in this video (https://www.youtube.com/watch?v=iHkKTGYc6aA&ab_channel=GreatScott%21, minute 8:30 and on) using same components. Now, what I need is really a DC output, whereas the output I get is AC (8-10kV, I assume): working with ZVS circuit is pretty new to me, hence I would like to ask if there was a method to rectify output current cheeply, without using high voltage bridge rectifier and capacitor after the transformer.

Nonetheless, there is no other way I've already tried searching for such components. My reasoning was the following. The input current of the circuit, as it is shown in the video, is about 400mA. Then, the current flowing through the primary of the transformer should have an RMS value of about 600mA. Since the power ideally is conserved, across the transformer, the output RMS current should be of I2 = (V1 / V2) * I1 = 0.8mA. Thus, I would need 4 diodes which can handle at least 10kV of reverse voltage and 0.8mA. I calculated the capacitance for the ripple capacitor using the formula C = I / (2 f Vpp) where V_pp is the peak to peak voltage of the ripple. The frequency of the ZVS circuit is about 42kHz. Setting Vpp = 1V, the capacitor should mesure C=10nF and should handle 10kV at least (which is a very difficult to find). Is this reasoning correct?

This is the circuit schematic from the video:

enter image description here

Thank you in advance for your answers, and excuse my English as I'm still practising it!

  • 2
    \$\begingroup\$ Please post the circuit into your question. Not the video but, a clear screen-shot of the circuit from the video. \$\endgroup\$
    – Andy aka
    Commented May 5, 2023 at 18:32

1 Answer 1


The same basic circuit, but applied to a winding on a CRT flyback transformer (FBT), will get you the required DC output. Aside from very early FBTs, there is a high voltage rectifier internal to these.

  • \$\begingroup\$ Thanks for your answer, but where can I find such transfomers? The transforming ratio is very extreme: 4V input to 15kV output, and most common electronics websites don't seem to have them. How should I search for them? \$\endgroup\$
    – Luke__
    Commented May 5, 2023 at 17:50
  • \$\begingroup\$ Replacement parts probably, or salvage one. I don't know what 4V you're referring to, unless you meant to put that in your question as a requirement? \$\endgroup\$ Commented May 5, 2023 at 19:57
  • \$\begingroup\$ Sorry, my mistake: the transformer used in the video is said to be capable of converting 4V to 15kV when searching on amazon, although I'm a bit skeptical on that... \$\endgroup\$
    – Luke__
    Commented May 5, 2023 at 20:31
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    \$\begingroup\$ @Luke__ -- Look for old discarded TV's. You could put an advertisement in a local paper, Craig's list, or ebay for an old TV. You can also try the local dump. Old big projection TV's have three, and CRO's (cathode ray oscilloscopes) also have flybacks. A few models of microwave ovens, too. \$\endgroup\$ Commented May 24, 2023 at 22:49
  • 1
    \$\begingroup\$ @Luke__ -- Hope you know what you're doing! You can easily kill yourself playing around with this stuff. Get your EE degree with concentration on high voltage first, before any more messing around with this stuff, is my very strong recommendation! Otherwise hire the expert you need. Look up Tim or another of the EE's here to hire them, but value your life, choose life, and don't die! \$\endgroup\$ Commented May 24, 2023 at 22:52

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