high voltage resister devider

[steven2]

this looks like it would qualify as the worlds biggest wire wound resister,
but this is a high voltage resiter devider, the pvc pipe base used to spiral wound the resister chain of 100x 10m 1/4 watt resisters to give a total resistance of 1000m, this stack will pull 50,000 volts dc
first the reisietr chain is carefully solderd each solder jiont carefully done, then the whole chain is coverd in heatshrink, for added insulation, it is then carefully wound around the pvc pipe base each spiral is measured to keep them the same distance apart ,then tacked with super glue to keep it in place evry few inchers along the spiral wound resiter chain.
the last ten m resiter is not coverd, as this is where the 2 wires are taped, one on each side of that resister the 2 wires are then run out the pvc pipe end and attached to 2x aligater clips, these go to your digital multimeter, set to 500vdc or 1000vdc. at the end of that same resister is a wire with aligater clip, it runs to the 0volts ground which is the safe end of the resister stack, at the opisite end of the pvc pipe with the insulated spiral wound 1000m resister chain is anothjer lead with aligater clip, this goes to the positive high voltage output of the flyback transformerthis stack of resisters devides the voltage by 100. when you measure across the first 10m resister.
you can encase the whole stack in epoxy for added safety, the ratio is allways 1/100 when you measure across the first 10m resiter, if the meter setup reads 28.3 volts. then the high voltage is actually 28.3 kilovolts. this sieries stack will pull 0.05ma at 50,000 volts power dissipation 2.5 watts or 0.025 watt per 120m , the total resistance of the sieries stack is 1000m. in the pictures here i have yet to fully finish this, more insulation and some sanding and decoration with green pvc for a neat appearence

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[steven2]

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[steven2]

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[audioguru2]

Hi Steven,
Good insulation, you'll not have any arcing on that stack. ;D

If your digital multimeter has a 10M ohm input resistance, then the voltage that it shows is only 1/2 of what it actually is. :

I'm sorry, but your math is wrong. 100 times 28.3V is not 28.3KV. It is only 2.83KV. But since the meter shows only half, the actual high voltage is 5660V. :'(

 

[steven2]

audio guru the information i used to biuld this high voltage resiter devider was sent to me in the mail by an email friend dr john sanderson formerly of monash university melbourne australia, now with csiro this is the first time i biult this i have yet to test it out

 

[steven2]

audio guru ive just tested it out with my multimeter set to its highest range 600 volts dc and with both probes attached to the high voltage resister devider i then then fired up the flyback full throttle and got a higher reading of 240 volts dc times 100 = 24000 volts dose that sound right to you there was no decimal points just 240

 

[audioguru2]

Hi Sparky Steven,
With your meter showing 240V, and if its input resistance is 10M (look it up, it is in parallel with your 10M measurement resistor), then your actual high voltage is a whopping 47,760V! ;D ;D ;D

 

[ante1]

Audioguru, Steven,

Do you think it would work just by omitting one resistor and use the meter in series as the one hundredth resistor? Presupposed that the meter have and input resistance of 10M which is very common. This way it would be easier to interpret the reading.

 

[steven2]

audio guru im a bit rusty with my maths, ive got papers around with ohms law calculations of resisters and voltage drops and current flows through resisters but i havent havent got around to studying it more, how did you work that out 47,760v i will add it to my formulae collection, ante if you read this, audio gurus the maths exspert i just biuld from information supplied to me dont have time to analyse it and give anserws i cant exsplain why all the high voltage stuff ive biult works ok, hey i use the continiuity checker alot dont bother to use the resistance thing as i think resisters never blow or burnout in things i biult ,and i use the transister tester to , so the trany tester and continiuity tester and another one is the n channel mosfet tester thats all i use in testing high voltage flyback driver circuits, when i biuld them. the circuits i biult these from are biult by those who did that ciircuit so i trust it when i biuld it , im planing another high voltage resister devider well 2 really, ones gona have a multimeter intergrated into it so it will be a whole unit the other is gona be made to look like a real resister but bigger and have 4 legs and will have colour bands so to others they would wonder where you get it from theres nothing like it around , the heatshrink tubeing on my unit really did well in preventing any arcovers and when you first put it on and heatshrink it you sometimes get trapped air bubles in it exspand and pop holes in it so i slip another bit on and seal it, now i c an intergrate these into a complete high voltage unit with hv digital meter to for instant voltage readings from the flyback transformer

 

[Ldanielrosa1]

I've been considering an HV probe for my DMM, but it would only be good to 20kV or so. My meter is not 10M input impedance, it varies. One time I tested it indirectly and found it to range from 9M5 to 11M. With this in mind I'd probably put it in parallel with a load resistor of 1M or less to limit the error.

 

[ante1]

Steven,

If you think about it this way you can rearrange the formula and start over. Sorry for doodling on your picture.

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[steven2]

l danielrosa and ante i welcome your input to this topic and audio guru to, anytime ill be doing some more but upgare the thing and include it in my next high voltage unit

 

[audioguru2]

Hi Ante,
I also thought of using the 10M meter as part of the voltage divider, but rejected it since it would be a serious and lethal hazzard if the meter's leads became loose during HV operation.

Hi Steven,
You must be certain that your meter's input resistance is 10M or my calculation doesn't apply.
I worked out the actual high voltage simply by using Ohm's Law:
1) Your 10M meter is in parallel with your bottom 10M resistor, so together equal 5M, as Ante shows.
2) 240V across 5M equals a current of 48 microamps.
3) The total of the series 99 10M resistors plus the 5M meter/resistor is 995M.
4) 48 microamps times 995M is 47,760V. ;D

Hi Ldanielrosa,
Your meter has a voltage divider in it too, so if its input resistance varies then it may not be accurate. ???

 

[steven2]

ante how did you do that, doodle on picture allready posted by me, thats cool you can add your modifications to any circuit posted the digital multimeter i used to measure this high voltage is the one with yellow case cover in these pictures ive got 2 multimeters the one i used on the right, is the one with 600 volts dc range maximin

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[ante1]

Steven & Audioguru,

Sorry but I don

 

[steven2]

audio guru thanks for the input i know about the parralell resisters 2x 10 in parralell=5m, your input is greatly apreciated

 

[audioguru2]

Hi Ante,
You are correct. The 48uA here is only 1/100th of the current (5mA) that a Ground Fault Interrupter is required to trip at, to prevent electrcution.

 

[ante1]

Audioguru,

Here our Ground Fault Interrupters is set for 30mA. I thought that was some kind of standard, maybe just in the EU then?

 

[steven2]

the sockets for my multimeter leads are secure, they wont come out, ante and audio guru