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Re: magnifiers
Tesla List wrote:
>
> Subscriber: Esondrmn-at-aol-dot-com Fri Jan 3 21:53:43 1997
> Date: Fri, 3 Jan 1997 13:48:32 -0500
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: magnifiers
>
> In a message dated 97-01-03 01:43:03 EST, you write:
>
> << Ed:
> Thanks for the input! I am already experiencing this condition with a
> 12kv. 30ma. neon! I've only tried raising the sec. about an inch or so,
> will play with more spacing. If convienient, you might look at a few
> more specs on my coil as stated in another message I have addressed to
> Bert and posted the same time as this message. Any comments you may have
> (several, I bet!) are greatly appreciated. Also, how does one determine
> crital coupling experimentally, or mathematically with our type of
> setups?
>
> Thanks again,
> Mike >>
>
> Mike,
>
> Sorry, I've lost the info on your coil. Several folks on this list have the
> equipment to measure and calculate the exact coupling of the
> primary/secondary. I have only done it by trial and error.
>
> Ed Sonderman
Mike,
Since you have a signal generator, you've basically got what you need.
Solder a pair of high-brightness LED's back-to-back. By connecting these
LED's in series with your signal generator to either the base of the
secondary (with the toroid in place) or across the tank caps with the
gap shorted, you can make all the necessary measurements to estimate k.
Secondary Fr:
Temporarily disconnect one end of the tank cap connection to the primary
winding. Remove the RF ground connection to the base of the secondary,
but otherwise have it installed inside the primary. Make sure you've got
the toroid in place and electrically connected to the top of the
secondary. Drive the base of the secondary through the LED's with the
signal generator. Increase the frequency from the lowest setting unitl
you get the first current peak. Adjust the frequency for the brightest
light from the LED's and record this frequency (Fr).
Primary Fr:
Now completely remove the secondary and put it in another room.
Reconnect the tank cap to the primary and temporaily short out the spark
gap. This will place the tank cap in parallel with the primary. connect
the ground of the signal generator to one cap terminal, and the other,
through the LED's, to the other. Now tune for the minimum light from the
LED's (antiresonant point). Adjust the tap setting on the primary until
this point is also the same as the secondary/toroid. Leave the gap
shorted and signal generator/LED's connected for the next measurement.
Coupling Factor(k):
Re-install the secondary/toroid and connect the RF ground to the base.
Carefully adjust the signal generator downward from Fr until you see
another minimum brightness point on the LED's. Record this frequency
(Flow). Now carefully increase the frerquency above Fr, and record the
next minimum brightness point (Fhigh).
You can now estimate the coupling coefficient(k) by making the following
calculation:
k = (Fhigh - Flow)/Fr
Best performance is reached when you get the highest k without
overcoupling (flashovers, sparks running up/down the coil...). Higher
values of k may require more sophisticated spark gap systems to
adequately quench. "Magic" k values that give better performance will
be:
0.22, 0.18, 0.153, 0.133
By adusting the height of the secondary relative to the primary, you
should be able to get close to one of these. Now disconnect your
measuring equipment, remove the short across the sparkgap, and carefully
tweak the tune for maximum output spark. Do so in a dark room so that
you can detect any signs of overcoupling. Excessive corona or flashovers
from the top of the winding to the primary is one sure sign of this.
Safe coilin' to you!
-- Bert --