Kilovolt Meter

Discussion in 'The Projects Forum' started by magnet18, Jul 28, 2011.

  1. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Alright, long story short I've reached a point where one of these would be dang useful, since there is little information out there about building them and they are REALLY expensive, I come here.

    So, I start with a 10 volt DC meter.
    Then add a rectifier, calibrate, add switch, and bam. It measures AC and DC.

    Then, add a 10:1 voltage divider, so it measures 100 volts.
    Then, add a 100:1 voltage divider (or a 10:1 on top of the existing 10:1). 1000V
    Then, add a 1000:1 I can measure 10KV
    Then a 10000:1, I can measure 100 KV
    and, the kicker, I would like to be able to measure up to 1000KV (X-ray transformers rate 140KV, and go higher, and theres marx generators and CW's and other stuffs, but this isn't about that).

    With a rotary switch to select one.

    Basically I end up with a GIGANTIC 1.21 GIGA OHM (not sure what resistance actually) resistor string tapped at various points, and a rectifier for measuring AC.

    So, does this sound do-able?
    Does anybody have any advice, words or wisdom, or anything that would help out with this at all?
     
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
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    megavolts may go unwanted places, like jump across your selector switch contacts, I don't know. It sounds too good to be true. At work I have an electrostatic voltmeter for measuring anything above 1000V. It's big, old, and very expensive.
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
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    Why not just buy a 40 kV probe? You can get them for on the order of $100 and they'll plug into your DMM. Fluke, B&K, and others make them.
     
  4. Jaguarjoe

    Active Member

    Apr 7, 2010
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    Waaaaaaaaaay back in the day, measuring the 2nd anode voltage on CRT televisions was all the rage. My dad made a 50kv job with a 20μA meter and a huge string of 22meg resistors all mounted in plexiglass panels, neatly spaced about an inch away from each other.

    Every car manufacturer routinely spray paints their cars electrostatically. Potentials range from 80kv for some troublesome basecoats up to about 120kv for clearcoat on a good day. Every one of their paint shops have HV generators and probes for testing them. Old technology HV generators were built into 5 gallon buckets filled with oil. Many feet of HV cable went from the generator to the aplicator which sucked. Newer stuff use "cascades", an oscillator, transformer and voltage multiplier mounted right on the aplicator with no HV cable, just a 0-20 analog input.

    Victoreen makes HV resistors, contact them, they'll know what you need.
     
  5. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Right, I figured that a megavolt was way too much, 100KV should be manageable though, if I use oil as a dielectric. It has been done
    - http://i.imgur.com/q9vc3.jpg

    @someonesdad... a $100 probe is not worth the money to me, especially to plug into my $10 harbor freight multimeter that can't accurately measure current.

    @jaguarjoe, thanks, I'll look them up :)
     
    Last edited: Jul 29, 2011
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Ohmite has resistors from 1k up to 50G that are good up to 90kv.
    http://www.ohmite.com/cgi-bin/showpage.cgi?product=supermox

    Working with HV can be pretty exciting, even if you supposedly have the right equipment.
    Back in the mid-70's, we were working in the hangar on some aircraft that needed fixing, and one of my fellow radar systems/missile fire control technicians had a HV probe connected to a Simpson 260 meter to check the 18.5kv supply for the main KPA (klystron power amplifier). But, he was on a metal work stand that happened to have one leg placed on a tie-down position, which was grounded. Anyway, he went to check the HV with that probe, and got a rude surprise that the test probe had a cracked barrel, and when he got zapped he did a 1-1/2 somersault backwards head-first into a trash can.

    Fortunately, he was OK.
     
  7. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I never mentioned a probe. I brought up the fact that I use one of these at work. Mine looks exactly the same but it goes much higher than 10KV. 100kv I think
     
  8. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    GAH, wrong user

    Thanks for the link though!
     
  9. debe

    Well-Known Member

    Sep 21, 2010
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    This is what i use , had it since the mid 70s. The earth lead needs to be securely conected when using as the HV can go places you may not want. Also have a simmilar X100 HV probe.
     
  10. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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