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Measurement Techniques


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From:  terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
Sent:  Tuesday, August 18, 1998 10:50 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: Measurement Techniques

Hi All,
        I though I would mention that my field probes are made "nicely" to
help the rather precise and high speed (100MHz) measurements I take.
However, only the resistive and capacitive loading on the antennas is really
important.  any "roughly close" component values will work.  Standard leaded
components won't hurt the readings very much.  Don't be intimidated by the
etched boards and such.  A very rough design of aluminum foil and cardboard
will give excellent results.  Any precision can be ignored for simple quench
measurements and such.  Of course, only one antenna is really needed for
such work.  Indeed, the original was a two way "CB" antenna with a 50 ohm
load resistor in parallel with the scope input.  This gives far better
results than hanging a wire off the scope by many orders of magnitude.

        Terry Fritz




At 04:43 PM 8/16/98 -0600, you wrote:
>Hi Tony,
>        I have information a field probes and fiber-optic probes at my site:
>
>http://www.peakpeak-dot-com/~terryf/tesla/experiments/experiments.html
>
>They are under the "A New Methode....." section.
>
>Main page at:
>
>http://www.peakpeak-dot-com/~terryf/tesla/main.html
>
>They will measure everything you mention.  The field probes are very easy to
>make and will do most of what you what.  The fiber probes (I now have a much
>better version) can measure all the primary currents and waveforms but they
>are fairly conplex to build.  The field probes are almost all I use any
>more.  A good 40kV DMM probe runs about $100.  A very nice thing to have.
>You can contact me off list also.  I am very involved with TC measurements
>and I "know" things.
>
>        Terry Fritz
>
>terryf-at-verinet-dot-com
>
>
>
>
>At 02:46 PM 8/16/98 -0400, you wrote:
>>I am getting close to final assembly of my first coil and I am looking
>>for information on measuring various characteristics.  I have a DMM.  I
>>can borrow an I-Scope, a current probe, and a signal generator, but I do
>>not have access to a high voltage probe.
>>
>>The coil will be powered by 3-4 15 Kv 30 ma NSTs.  The secondary is
>>8.4"x40".  The cap is a .0228 ufd pulse discharge cap.
>>
>>I have seen bits of information on this in other posts, but I am looking
>>for more complete ideas on measurments.  There are many things I would
>>like to measure but the following is an initial list in decreasing order
>>of importance:
>>
>>-Secondary coil resonant frequency
>>    I plan to do this with the equipment I have
>>
>>-Primary current waveform
>>    I need this to monitor gap quenching.  I am using NSTs and don't
>>have any part of the primary grounded.  How can I measure this without
>>damaging the O-Scope?
>>
>>-Secondary current waveform
>>    I should be able to measure this at the base of the coil with the
>>current probe.  I may need to build a new current probe from a small
>>toriod and shield the leads so that I can get the O-Scope far enough
>>away for safety.
>>
>>I have seen comments about building field probes.  I am looking for
>>details on this.  I am also looking for practicle suggestions on
>>triggering.
>>
>>I hope to measure the secondary resonance next weekend, 8/22, and have
>>the coil running sometime in September.
>>
>>                Thanks,
>>                Tony Lekas
>>
>>
>
>