# Cockroft-Walton question.

#### RGClark

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

Related Electrical Engineering News on Phys.org

#### berkeman

Mentor
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

#### Random

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 cant start withl 12 v and multiply your way to 12 MV.

#### Antiphon

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.

#### berkeman

Mentor
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.

#### Antiphon

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.

#### berkeman

Mentor
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 seperate 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-

#### CharlesP

Need 3 phase

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

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving