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Re: quenching at the first notch


From: 	Scott Stephens[SMTP:stephens-at-enteract-dot-com]
Sent: 	Tuesday, November 25, 1997 11:46 AM
To: 	Tesla List
Subject: 	Re: quenching at the first notch

At 09:45 PM 11/20/97 -0600, you wrote:

>>Subject: 	quenching at the first notch
>>
>>I got these lines from one of the posts
>>
>>>it definately did not quench at the first notch (don't recall exactly when it
>>>was).  I understand that failing to quench at the 1st notch implies multiple
>>>pri-sec power transfers and loss of efficiency therein.
>>
>>
>>could someone please explain to me quenching at the first notch, what
>>happens when it doesn't, how do you know it's happening, and how you can
>>make it so it does?
>
>
>One can determine at which notch his coil quenches by observing on an
>oscilloscope the secondary energy.  Usually one just has to have a scope
>probe dangling several feet away from a TC to pick this signal up, no
>direct connection is necessary or recomended.  

Do you trigger your scope off the spark gap? I bet jitter from a spark gap
is awfull.

>The hard part is how to get your coil to quench at the first notch.  It
>is probably not even possible to quench at the first notch on all coils,
>(maybe none?).  Things that affect this are:
>1) Coupling between pri & sec coils, as measured by "K".
>2) Spark gap geometry and airflow.
>3) Power level.
>4) The nature of (and if) sparks break out from your top load.


And I would add, the tuning of each coil.

>
>I wish I could be more specific on these points, but this is where my
>science fails and black art and luck take over.

I read a good Tesla article in "A high potential Tesla coil impulse
generator for lecture demonstrations and science exhibitions by Kenneth
Skelden, Alastair Grant and Slan Scott, in that great little American Journal of
Physics, 65 (8) August 1997, pages 744 to 754." recommended and graciously
offered by Winfield Hill.

In this article, a detailed (and quite mathematical) analysis is given for
the energy transfer bewtween the coupled tuned circuits. So science doesn't
fail to describe the notches, and you can design the period of the AM
modulation, so your coil will quench better.

I've found that the science fails and the art takes over when you actualy
attempt to build and tune! I like the equations in this article, because the
Medhurst coil self capacitance and resonance equations were acurate, where
as equations I got at the funet.fi tesla archive were not.