Strange High Voltage Multiplier Result

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Dennis P Brown
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Real name: Dennis Brown

Strange High Voltage Multiplier Result

Post by Dennis P Brown »

When building the 100 kV voltage multiplier (VM), I built the first stage using an older system that had fed a full wave VM. As such, I was careless and assembled the first stage incorrectly. As I always do, I test each stage before adding any additional stages so discovered this mistake before it could cause issues.

See the photo and ignore the door knob system - it wasn't installed for the first stage test. The mistake is that I used two diodes to feed one cap and the second diode is feeding the HV cap on the left side (each diode's correct "flow" is toward the center of the photo.) Of course, in a classic system, only one diode is used to supply the high side of the cap (and it is anchored on the ground side, of course.) So, essentially, in the system in the photo I have two cross feeding diodes that each supply one side of a single capacitor (and this one is on the ground side of the system.)

When I measured the voltage output for this incorrect single stage VM, the max value was 20 kV! Yet the NST can only produce 7.5 kV at best (center grounded.) This was a single stage VM (while it has two caps each side they are in series to up their voltage since these individual caps can only handle a max of 10 kV.) I am confused that the system tripled the output rather than doubled it. One side of the NST is ground (besides the center tap.) This ground was NOT floating so the x-former was at ground potential at all times.
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NST x-former and its diodes/caps (the caps on the x-former case are doubled in series.) The stack ground is on the left side connected to that x-former output
NST x-former and its diodes/caps (the caps on the x-former case are doubled in series.) The stack ground is on the left side connected to that x-former output
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Richard Hull
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Re: Strange High Voltage Multiplier Result

Post by Richard Hull »

15kv neon center tapped so 7.5kv rms. Two diodes feed the first cap. (full wave rectification) 7.5 times 1.414 = 10.6kv peak. Simple, single stage followup doubling = 21.2kv output (no load)

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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