# Measuring secondary voltage (fwd)

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From:  John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent:  Friday, January 23, 1998 4:18 PM
To:  Tesla List
Subject:  Re: Measuring secondary voltage (fwd)

At 11:29 PM 1/22/98 +0000, you wrote:
>
>----------
>From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent:  Thursday, January 22, 1998 2:22 PM
>To:  Tesla List
>Subject:  Re: Measuring secondary voltage (fwd)
>
>Hi all,
>        I've been following the discussion on Vout with much
>interest. There are a couple of parameters directly involved in long
>sparks from TCs which only one or two have mentioned:
>
>- First is break rate. The voltage doesn't increases but the sparks
>sure do as break rate is upped

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The sparks increase in length and the necessary input energy increases.
The equation is

J = .5 Cp x Vp^2 x BKS / eff

assuming other parameters unchanged.

JC
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>>   Jim -
>>
>>   Wouldn't "extrapolating to infinite impedance" give you infinite voltage?
>>
>>   However, I believe your idea could be used by extrapolating to a very high
>> impedance where the reduction in voltage could be negligible.
>>
>>   Maybe Robert Stephens would want to try this. It certainly could be used
>> for small coils.
>>
>>   John Couture
>
>I think the last system that one should attempt to extract an
>accurate figure from is a small one. IMHO, a large system (one with a
>large Cself) running at much reduced Ep to bring it into the measuring
>range of test equipment would be the best option. For one thing,
>large Cself minimizes the influence of divider probes and the like.
>Is there any reason why the result could not be extrapolated to
>high values of Ep if an accurate measurement at low Ep could be made?
>
>?
>Malcolm

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A large coil would be better. But reducing the Ep could cancel the advantages.

Extrapolating the Ep sounds like a good idea and might work if the Ep can
be raised to verify some the of curve.

However, preventing sparks across the voltage divider will be a problem
as Bill Lemieux pointed out. Hopefully Robert Stephens has the answer.

What we are trying to do is what high voltage engineering labs do every
day. This test apparatus cost millions of dollars but is not capable of
testing Tesla coils. It is obvious we have to resort to our own ingenuity