How Can a Cockroft-Walton Voltage Doubler Be Modified for Higher Multiplication?

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Discussion Overview

The discussion revolves around the modification of a Cockcroft-Walton (CW) voltage doubler to achieve higher voltage multiplication. Participants explore the feasibility of cascading multiple stages and the implications of using AC versus DC outputs in this context.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that cascading the output of a CW voltage doubler into another doubler could theoretically allow for exponential voltage multiplication, proposing a multiplication factor of 2^10 with 10 stages.
  • Another participant agrees that multiple stages can be used, but warns that the effective series resistance may limit the practical voltage achievable.
  • Concerns are raised about the nature of the output, with some participants stating that the output is DC, which would prevent the proposed cascading method from working as intended.
  • A participant clarifies that while AC outputs could allow for cascading, the CW voltage doubler typically produces a DC output, which limits the multiplication method suggested by the original poster.
  • Further discussion reveals confusion regarding the charging of capacitors in the circuit, with one participant acknowledging a misunderstanding about the output being effectively DC despite AC currents through the capacitors.
  • A later comment introduces the idea of needing a three-phase circuit for the application, prompting a request for specific circuit details.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of cascading voltage doublers and the nature of the output. There is no consensus on whether the proposed method of cascading is valid, and the discussion remains unresolved regarding the best approach for achieving higher voltage multiplication.

Contextual Notes

Limitations include the dependence on the type of output (AC vs. DC) and the impact of series resistance on the effectiveness of cascading stages. The discussion does not resolve these technical nuances.

RGClark
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Why couldn't you have the output of a CW voltage doubler lead into the
input of a another doubler? It seems to me that instead of the voltages
being additive with additional stages as done now, with this method you
could double the voltage each time.
So with 10 repetitions you could multiply the voltage by 2^10 = 1024.


Bob Clark
 
Engineering news on Phys.org
I think you can have as many stages as you want, as long as the ladder method is an efficient enough voltage multiplier for your needs. Where did you read that you can't cascade the ladder?

http://www.blazelabs.com/e-exp15.asp
 
Yes, you may have as many stages as you can feed - at some point however the effective lumped series resistance will start to defeat your efforts.. so you can't start withl 12 v and multiply your way to 12 MV.
 
What you want to do doesn't work because the output of the newtork is DC, not AC.

If you had a voltage doubler with an AC output, the stages could cascade exponentially as you describe.
 
Antiphon said:
What you want to do doesn't work because the output of the newtork is DC, not AC.

If you had a voltage doubler with an AC output, the stages could cascade exponentially as you describe.
I don't think that's right Antiphon. The voltage multiplier that the OP is asking about is a half-wave rectifier/multiplier:

http://www.blazelabs.com/e-exp15.asp

I suppose if you follow the last AC stage with a single diode and then a capacitor to ground, that will give you a DC output. But if you keep following the ladder structure of diodes and caps, the AC pulses get passed up the ladder.
 
Actually, no. If you look at the polarities of the caps, they are all charging with the
positive side on the right. The output will be DC.
 
Antiphon said:
Actually, no. If you look at the polarities of the caps, they are all charging with the
positive side on the right. The output will be DC.
Oh, I see where I was confused. There are AC currents through the caps, but the result is indeed pretty much DC at the output. I misinterpreted the OP's question -- he was asking why it wasn't more efficient to series connect separate doublers instead of just adding more stages. Yeah, the C-W multiplier only grows by adding stages, not by trying to cascade separate ones somehow. Thanks Antiphon. -Mike-
 
Need 3 phase

OK now what is the circuit for a three phase machine? Powered by three phase RF hopefully.
 

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