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Re: 10 tests and suddenly...RRRAAAATTTTT!!!
Subject: Re: 10 tests and suddenly...RRRAAAATTTTT!!!
Date: Mon, 12 May 1997 14:06:46 +0200
From: tesla <tesla-at-ixx.se>
To: Tesla List <tesla-at-pupman-dot-com>
>Congratulations on first light, Matt! There's really nothing like seeing
>(and hearing!) the coil you've built from scratch really work! From the
>sounds of it, you'll really need that strike rail again!
Thanx.
Yes, i have to do some modifications now that it works. You know, the
funny
thing is that i didn't have any strikes towards the primary at all, even
though the lenght between pri. and sec. was way below striking distance.
I think some of it has to do with the single strip of conductive tape i
have put around the outside of the toroid(to connect all the strips of
aluminum electrically). All sparks seemed to emanate from the center so
to
speak. Maybe an idea for others to try??
>I assume you meant your coil diameter was 16.5cm and not 16.5 mm. :^).
>For my conveniance, I've converted the Metric values to English. I've
>also tried to "read between the lines" on your coil parameters.
Yes, of course i meant cm, I was probably too excited that night.
You know how it is.... =)
>Toroid: 27.5" x 4.5"
>Est. Toroid Capacitance (20% derating assumed) ~ 19pF
>Secondary: 24 AWG, 23.6" high, 1000 turns, 6.5" outside diameter
>Estimated secondary Inductance ~ 40.5 mH
>Estimated secondary Self-Capacitance ~ 10.5 pF
>Estimated Unloaded secondary Fo ~ 244 kHz
>Estimated Loaded (secondary + toroid) Fo ~ 146 kHz
>
>(Note: Have you tried measuring your actual secondary-toroid Fo with a
>signal generator and LED-pair?)
Hmm, how do i do this???
>Primary: Tubing Diameter = 0.3"
>Ctr-Ctr Spacing = 0.39 + 0.3 = 0.69" (Assumed)
>Inner diameter: 8" (Assumed)
>Number of Turns: 10
>Estimated Inductance = 41 uH
>Primary Cap Size = 29.3 nF = 0.0293 uF
>Primary Fo ~ 145 kHz
>
>(Note: I assumed you meant you had 1 cm of clearance between primary
>turns... If your ctr-ctr spacing was only 1 cm, I can understand why you
>might be running into primary turn-turn arc-over problems).
Yes, 1cm spacing between primary turns is correct.
>
>Conclusion: Primary Fo ~ Loaded Secondary Fo ~ 145 kHz. Lookin' Good!
>
>>From the looks of it, the parameters you're using look to be "right on"
>for a good running coil! Are any of the above assumptions I've made in
>error? If not, compare the various values with what your calculated
>values are, and we can see where any problems lie in your design tools.
>Relative to basic 2-coil design, the basic design parameters are pretty
>well "shaken down", and practice pretty closely matches theory. It's
>when you get into the subtleties or try to maximize sparklength versus
>input power that the "black magic" starts creeping in... :^).
All values seem to be correct except for the number of primary turns.
10 was the original number but after our modification with the strike
rail we had 12 turns.
//Matt