Pushing a CW Multiplier
- Dennis P Brown
- Posts: 3160
- Joined: Sun May 20, 2012 10:46 am
- Real name: Dennis Brown
Re: Pushing a CW Multiplier
I considered it - oil filled plastic tubes with a center HV wire from the voltage multiplier tank all connected to a small sphere for corona discharge; then sense the field using my 45 kV probe. The issue was that I felt the voltage multiplier had far too much power to safely get near. Not sure how to create a dummy load that would work in a safe manner - a really long Giga-ohm and long mega-ohm resisters under oil to act as a voltage divider connected to the VM output? We are talking a 100 kV or more with a large surge current (low frequency). I haven't abandoned the approach or project completely (that is why its still assembled in its plexiglass tube/tank. ) Any ideas would be appreciated.
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- Posts: 505
- Joined: Thu Sep 23, 2021 10:36 am
- Real name: Matt Gibson
Re: Pushing a CW Multiplier
I decided to revive this…
Instead of leaving this as a 10 stage designed for 100kV at 1mA, would it be worthwhile to convert to a 5 stage and double up/parallel on the capacitors?
I’d go from 10 stages, 0.015uF capacitors to 5 stages and 0.03uF capacitors. Running through https://www.extremeelectronics.co.uk/ca ... alculator/
I see less than 1600v dropped at 15mA (24w wasted). Seems reasonable, no? Capacitors are rated for 15kV and diodes are rated for 30kV. I should have no problem pushing 60-70kV?
100kV at 1mA doesn’t seem very useful and I’ll probably never tackle 100kV insulation.
Instead of leaving this as a 10 stage designed for 100kV at 1mA, would it be worthwhile to convert to a 5 stage and double up/parallel on the capacitors?
I’d go from 10 stages, 0.015uF capacitors to 5 stages and 0.03uF capacitors. Running through https://www.extremeelectronics.co.uk/ca ... alculator/
I see less than 1600v dropped at 15mA (24w wasted). Seems reasonable, no? Capacitors are rated for 15kV and diodes are rated for 30kV. I should have no problem pushing 60-70kV?
100kV at 1mA doesn’t seem very useful and I’ll probably never tackle 100kV insulation.
- Rich Feldman
- Posts: 1470
- Joined: Mon Dec 21, 2009 6:59 pm
- Real name: Rich Feldman
- Location: Santa Clara County, CA, USA
Re: Pushing a CW Multiplier
Sounds like you are planning to reconfigure a kit of high voltage C's and D's.
When you figure the stack's voltage drop under load, beware of calling it "lost power"
or, as mentioned by someone early in this thread, saying that the I * dV product heats the components.
It's reactive voltage drop, without power dissipation if the D's and C's are ideal.
Real D's and C's are not ideal.
The C's have ESR and dielectric loss which figures into their RF current ratings, as Tesla coilers know well.
The D's have forward dV when on, and reverse I while turning off.
But those are not, AFAIK, major contributors to the output resistance of practical voltage multipliers.
When you figure the stack's voltage drop under load, beware of calling it "lost power"
or, as mentioned by someone early in this thread, saying that the I * dV product heats the components.
It's reactive voltage drop, without power dissipation if the D's and C's are ideal.
Real D's and C's are not ideal.
The C's have ESR and dielectric loss which figures into their RF current ratings, as Tesla coilers know well.
The D's have forward dV when on, and reverse I while turning off.
But those are not, AFAIK, major contributors to the output resistance of practical voltage multipliers.
All models are wrong; some models are useful. -- George Box
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- Posts: 505
- Joined: Thu Sep 23, 2021 10:36 am
- Real name: Matt Gibson
Re: Pushing a CW Multiplier
Rich,
That’s what I’m up to…Going from 10 stages to 5 stages frees up enough capacitors to double up. I’d simply remove the extra diodes and keep them as spares.
My thoughts are that 5 stages should be a lot less “lossy” than 10 stages and this multiplier wouldn’t need oil since it was designed for 100kV in air use.
Any reason this won’t work or be an exercise in futility? First glance, this looks like a nicely packaged up option to get a 60kV supply that can source some decent current, all without needing any oil. I might need to blow some air across the boards for cooling…
That’s what I’m up to…Going from 10 stages to 5 stages frees up enough capacitors to double up. I’d simply remove the extra diodes and keep them as spares.
My thoughts are that 5 stages should be a lot less “lossy” than 10 stages and this multiplier wouldn’t need oil since it was designed for 100kV in air use.
Any reason this won’t work or be an exercise in futility? First glance, this looks like a nicely packaged up option to get a 60kV supply that can source some decent current, all without needing any oil. I might need to blow some air across the boards for cooling…