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Re: [TCML] Scoping Quench

Hi Gary,
I'm interested in the construction of these fiber-optic probes.  Do
you have a link?  I had trouble finding it in the archives.


On Sun, Nov 22, 2009 at 4:06 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> Hi Greg,
> For the scope-shots of my primary waveforms, I used one of the fancy fiber-optic probes that Terry Fritz designed way back when...  This was not a casual bit of construction and I never did achieve a stable and reliable vertical calibration.  That is the only way I know of to get an accurate HF measurement of the primary side stuff.  It may be possible to connect a "suitable" HV scope probe ground clip to the NST case (RF ground) and float the mains-ground, and measure one side of the NST for an approximate one-half measure of the cap charging voltage, but the HF response may be poor.  I concur with the advice of others - that quenching behavior can be accurately inferred from the secondary field.  That was the basis for my comments about my sucker gap quenching behavior.
> One might be able to design some sort of optical pickup to the gap, but we're typically interested in scoping what goes on beyond the point of quench as well, and who needs another project?  I think if I were to invest some time in an optical pickup, it would be something with a low-pass filter, that plugs into a garden-variety frequency counter, to permit a quick BPS measurement.  Amazing that hasn't been done yet!
> Regards, Gary Lau
>> -----Original Message-----
>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>> Behalf Of G Hunter
>> Sent: Saturday, November 21, 2009 11:19 AM
>> To: Tesla Coil Mailing List
>> Subject: Re: [TCML] Scoping Quench
>> Howdy Scot,
>> > hey Greg..
>> >
>> > If your coil is putting out streamers comparable to other
>> > coils of the
>> > size and power, its quenching  :)
>> Sure, it's quenching somewhere, but where?  1st notch?  4th notch?  I want to see
>> for myself.  It's not an urgent matter.  I'm just curious.
>> Also, good sparks don't automatically imply good quenching.  While analyzing his
>> single static sucker gap, Gary Lau discovered that even with crappy quenching, a
>> Tesla coil can produce satisfactory streamers.  Hey Gary, how did you scope that
>> without killing your scope?
>> > Attempting to put an O-scope on a primary ( or even near a
>> > primary)
>> > could lead to the death of the scope...
>> Yeah, I've thought of that.  My scope is a Japanese relic from the late 70's.  I gave
>> $45 for it.  If it croaks, I'll get over it.
>> What about optical probing?  Could I rig up a photo diode coupled to the input
>> channel on my scope and let it "watch" the spark gap?  Does the spark gap arc
>> accurately reflect spark gap performance?
>> > hi voltage from the supply itself, EMP EMF from the
>> > primary, inductive
>> > voltages etc... are things to consider
>> > O-Scopes, even tho most are shielded, can be influenced by
>> > exterior
>> > sources. Mine can give erratic readings if I have a
>> > fluorescent lite too
>> > close to it.
>> >
>> > See what other people have to say about protecting a scope
>> > in that
>> > situation.... Ive never done it due to the fear of trashing
>> > mine...
>> >
>> > Scot D
>> Cheers,
>> Greg
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Henry Hallam

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