Voltage Multiplier Circuit Design

[ayaz15m]

Ok thanks. So with hv input, my output should be somewhere around the theoretical value?

 

[chemelec]

This is the biggest Multiplier I Built.
Output Over 130 KV.
This whole unit was summerged in Transformer Oil for Insulation.

 

[chemelec]

Ok thanks. So with hv input, my output should be somewhere around the theoretical value?

1) Depends on your Input Voltage.
2) Maybe Also Frequency?
What are those Diodes Rated for?
3) What input voltage and Frequency?
4) What Output Voltage at What Output Current do you expect?
5) What is your Load?
And How do you expect to measure this Output Voltage?


The HV Multiplier Unit I Posted above uses High Frequency Diodes and Input Frequency was about 20 or 30 Khz.
Can't remember exact current but was considerable at 130 Kv.

 

[ayaz15m]

What did you use as your input ac source?

 

[chemelec]

You never answered my Questions!

I built all of this unit about 20 Years ago, for another company I was under Contract for.
So because of Time, my memory is lacking a bit on some details.

It was driven with a High Frequency Switching Power Supply, that I also designed.
I believe it was rated at about 800 watts.
The Output Transformer I made for it was also Oil Filled to prevent Corona discharge.

 

[jjw]

**broken link removed** View attachment 86068 **broken link removed**
Look at THESE.

The Diodes I used are 1N4005's
Brown Cap = .02 uF
Blue Cap = .43uF
Input was 120 VAC
Output is Not Quite the 336 volts, but Close to it.
There are always some Losses because of Diode Voltage Drops and Filtering.

I did not check the others, but the voltage doubler schematic is wrong.
The first diode prevents charging of C1 to negative voltage.It should be replaced by wire.
Also in your working circuit you have only two diodes.

 

[chemelec]

Sorry About That, Don't know how I didn't see that error.

 

[ayaz15m]

Thanks so much for all your help so far. Ok so I built my circuit and put it in mineral oil and hooked up my hv transformer. I wanted to test the circuit so I let the output arc. It is fine for about 3-5 seconds but then the first capacitor where the hot wire connects blows out, but all the other ones are fine. My capacitors are rated a little more than twice the input voltage. Any ideas?

 

[chemelec]

Possible Problems:

1) The Voltage Ratings on your Capacitors are Probably a DC Rating.
Your input is AC.
I Would recommend a Capacitor with a rating of 4 Times the input Voltage.
Or one that is Actually rated at AC Voltages.

2) Or your circuit is just not suitable to create a continuous Arc on the output.

Without Knowing your Exact Circuit with Part Values, Plus Input Voltages and Frequency, it is Impossible for me to give you better advice.

One Other Option is to Connect a Filament type LIGHT BULB (Possibly a 100 WATT Bulb) in Series with the Hot Wire Input.
This will Limit your input Current to a Safer level.

 

[tvtech]

View attachment 86083
This is the biggest Multiplier I Built.
Output Over 130 KV.
This whole unit was summerged in Transformer Oil for Insulation.

That's a neat piece of work Gary

Regards,
tvtech

 

[chemelec]

That's a neat piece of work Gary

Regards,
tvtech

THANKS.
The Diodes on that board are rated at 20 KV and 100 mA
and those caps are 820 pF and 30Kv.

 

[ayaz15m]

Possible Problems:

1) The Voltage Ratings on your Capacitors are Probably a DC Rating.
Your input is AC.
I Would recommend a Capacitor with a rating of 4 Times the input Voltage.
Or one that is Actually rated at AC Voltages.

2) Or your circuit is just not suitable to create a continuous Arc on the output.

Without Knowing your Exact Circuit with Part Values, Plus Input Voltages and Frequency, it is Impossible for me to give you better advice.

One Other Option is to Connect a Filament type LIGHT BULB (Possibly a 100 WATT Bulb) in Series with the Hot Wire Input.
This will Limit your input Current to a Safer level.

Well, to test it out I made a voltage doubler from the corrected diagram above. I spoke with one of my buddies who is an electrical engineer and he thought it was odd that only the first capacitor was blowing out.

Parts:
transformer (input ac) - 9000 V , 30mA , 60 hz
capacitors - 2.2 nF , 20 kV also have some 1.5 nF , 20 kV (for this circuit I used 2 of the 2.2 nF caps)
hv diodes - 20kV

The current is not that high at all so I am not sure if a light bulb will help, but if you still do at this current I can try it out.

Also, I was wondering since my transformer has a hot and neutral lead going into the circuit some similar diagrams I found online are also grounded, so should I ground the neutral lead?

 

[chemelec]

No Forget the Light Bulb.

I Also find it Strange that your only Damaging the First Cap.
But as I Said: Your Caps are rated at 20 KVDC.
NOT a 20 KVAC rating.

The AC Rating of those Caps May be LOWER than the 9000 volts your putting in, so causing damage to it.

The Second Cap will Not be Seeing the full Pure AC, so that may be saving it from damage.

As far as GROUND goes, Since your using a Transformer, your 9000 Volts is probably Isolated from ground.
There really is no Hot or Neutral.
It does Not matter if you Ground it or not.
But if you do, that is also ok.

Considering your 2.2 nF caps. (.0022uF)
That is pretty small capacitance for working on 60 Hz.
It has a Capacitive reactance of 1,326,291 Ohms at 60 Hz.

 

[ayaz15m]

Thanks for your help. Does anyone know anything about vacuum tubes?

 

[chemelec]

Thanks for your help. Does anyone know anything about vacuum tubes?

YES, So what is your Question?

 

[ayaz15m]

Ok so I want to operate vacuum tube using my multiplier circuit. I have 2x2a tube, which is a half wave diode. There is one anode and one cathode. There are a total of four pins on the bottom two of which are not used and the other two are heater pins, one of which is the cathode. Please see attached file about tube. I am trying to operate the tube in cold cathode mode. I know the positive output of the multiplier will attach to the cap(anode). I am not sure what to attach to the cathode or the heater pins, will I attach the negative output of the multiplier or ground it?

 

[chemelec]

CIRCUIT Attached

 

[ayaz15m]

But if you have 2.5 volts going to the filament you are heating it and that is not cold cathode mode.

 

[ayaz15m]

Ok I think I have it working. I attached the hv positive to the anode and hv negative to cathode. I tried it out with 15 kv dc and got a faint blue glow.

So next I want to find out in the diagrams you posted above you said the cx(last capacitor) needs to be rated higher than the output voltage. So in my case I need a 40 kv cap because my output should be 38 kv. How crucial is to have it at that rating? Is it possible to use two caps rated at 20 kv each to get 40 kv. So based off this in the multiplier you made, was your last cap rated at 130 kv or did you do something else?

 

[chemelec]

LOOK HERE

https://www.dangerouslaboratories.org/xray1.html

BUT DEFINATELY CONSIDER THEIR WARNINGS!