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Measuring C, HV Resistors, etc.
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From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Monday, June 08, 1998 11:30 AM
To: Tesla List
Subject: Re: Measuring C, HV Resistors, etc.
to: Steve
Happen to have a tel number and address for Tech America??
DR.RESONANCE-at-next-wave-dot-net
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Measuring C, HV Resistors, etc.
> Date: Sunday, June 07, 1998 10:21 PM
>
>
> ----------
> From: Steve Young [SMTP:youngs-at-konnections-dot-com]
> Sent: Saturday, June 06, 1998 11:42 PM
> To: Tesla List
> Subject: Measuring C, HV Resistors, etc.
>
> To all,
>
> 1) Every now and then, someone posts their need for inexpensive way to
> measure C. A great source for all sorts of parts is Tech America. Their
> catalog is available at Radio Shack, or you can get one via their website
> at www.techam-dot-com. They sell a kit (part number 990-0043) for $13 which
> lets one use a DVM to measure 2pf to 2 mf.
>
> 2) Occasionally, coilers indicate a need for HV resistors. If you don't
> mind a lot of soldering, you can make your own very cheaply. Tech
America
> sells resistors for 100 for a dollar. Use 1/2 watt resistors which have
a
> rating of 350 volts. For example, suppose you have a 20,000 ohms per
volt
> meter which can measure 5 KV, but you want to measure up to 15 KV. Just
> add 67 3 meg 1/2 watt resistors (200 meg) in series with the test lead
and
> presto, you have a 15 KV meter. Cost is 67 cents. The resistor string
> will be good for at least 23 KV and can dissapate 20+ watts. Be sure to
> arrange the ends of the resistor string so the HV doesn't flash over
> possibly resulting in a fried meter. It would help to put the string in
> oil to reduce corona and improve heat dissapation.
>
> If you don't care about the exact value of the HV resistor, then another
> easy solution is to use plastic tubing filled with tap water. Push wires
> through plugs in the ends of the tube. Such resistors work great in a
Marx
> generator, for example. Just be sure the wires in the tube are at least
a
> few inches apart so they don't arc over and explode! Even though the
> resistance is not very predictable, you can still make an accurate
voltage
> divider. For example, a hundred foot hose with a electrode pushed
through
> at the 1 foot spot would make a 100:1 voltage divider which could handle
> many KV.
>
> 3) Tech America has just started carrying a line of Amidon toroidal
cores.
> Biggest ones are 2 inches O. D.
>
> --Steve
>