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First Coil - No Sparks
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From: Barton B. Anderson [SMTP:mopar-at-uswest-dot-net]
Sent: Thursday, June 11, 1998 12:52 AM
To: Tesla List
Subject: Re: First Coil - No Sparks
DJ,
My 2 cents:
I calculated your coils unloaded frequency at about 707khz and loaded (toroid)
at 328khz. I also calculated the system should tune at about 9 turns (~47uH).
The toroid is pretty large which may be making the system difficult to breakout.
The toroids capacitance calculated to 20.5pF. I couldn't help but notice you
tried at 4" and 8" above secondary. This is probably too high to start with. You
may want to first try to jump a point-to-point arc (add <nail - whatever> to
toroid and arc to RF ground rod) with the bottom of the toroid parallel with the
top winding to get started with.
Just some thoughts,
Bart
Tesla List wrote:
> ----------
> From: djQuecke [SMTP:djQuecke-at-worldnet.att-dot-net]
> Sent: Monday, June 08, 1998 8:07 PM
> To: Tesla List
> Subject: First Coil - No Sparks
>
> I just completed my first coil yesterday but I'm not getting any discharge.
>
> 4.3" x 21.625" secondary - 22awg - 10 coats laq before winding then 15 more
> coats. Ground via 10' flat braided cable to 10' of #4 stranded to 8' ground
> rod.
> Started with slight overcouple. Moved incrementally up to 1/4" above first
> primary turn (no affect).
>
> 19"x4" toroid - Foil tape over foil over dryer duct and pizza pans. Tried
> 4" - 8" above final turn on secondary.
>
> 1/4" copper tube primary, spaced 1/4" 15 turns total - tried tap at several
> spot on turns 14 and 15. 15 degree rise. Just over an inch between first
> turn and secondary.
>
> 15kv 30ma NST
>
> NST protection -
> A 500ohm/65w resistor from each NST lead
> 1000pf ceramic caps across resistors
> 3.5mh coil on each leg (one coil showed "minor" shorting so I removed
> both from circuit without affect)
>
> Safety gap - across NST (actually more like two gaps, one from each leg to
> ground)
> I set gaps so they just barely didn't fire with NST alone. During runs, gap
> would go off almost non-stop, I adjusted so that it didn't go off, no change
> on output, readjusted so it goes off intermittently (once every 2 or 3
> seconds)
>
> Main gap - RQ static 6"x9x2" (8 gaps total) tested at 7 gaps in use)
>
> Caps - 4 Oil filled poly each rated around 5300pf, 7500v, wired 2 pair in
> series then the 2 pair are paralleled. Value tested at 5240pf on a decent
> LC digital meter.
>
> Power controlled by 10a variac.
>
> There appears to be a great voltage increase if intensity of safety gap
> discharge is a correct indicator. Main spark gap is firing and appears to
> be doing what I expected.
>
> All settings have resulted in zero output. I had hope to be ballpark close
> and adjust from there but apparently, I'm not even on the field yet.
>
> Thoughts?
>
> Thanks,
>
> dj