Freaky frequency

From: 	DR.RESONANCE[SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: 	Wednesday, June 18, 1997 11:37 PM
To: 	Tesla List
Subject: 	Re: Freaky frequency

TO: Erik Hennix

50 ma. of drive current for a .022 MFD cap is not enough.  You need a
minimum of 120 ma. of drive current (voltage not as important if in the
6-12 kv range) to drive this system.  Then you can use your larger terminal
and get some longer sparks.

Hope this points you in the right direction.


> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Freaky frequency
> Date: Tuesday,June 17,1997 6:16 PM
> Subject:  Freaky frequency
>   Date:   Tue, 17 Jun 1997 08:20:08 PDT
>   From:   "Erik Hennix" <mr_white-at-hotmail-dot-com>
>     To:  tesla-at-pupman-dot-com
> Hi everyone!
> I've been getting some strange results while tuning my
> coil. I'll first state the specifics of my system.
> Secondary coil: 
> 11cm PVC pipe wound with approx 810 turns 
> of 0.6mm magnet wire. About 37 turns per inch.
> Sealed with clear plastic laquer.
> Primary coil.
> Cone shaped with 60 degrees banking and 15 1/2
> turns of 1/4" soft copper tubing. The hypothenuse being
> 22.5cm in length and the inner (lowest) turn 15cm in
> diameter. 
> Capacitor:
> Vertical plate type made of polyethene and aluminum foil
> and immersed in motor oil. I've measured the capacitance
> (using line voltage and a mA meter) to 0.022uF.
> Power supply:
> Two 3920V 50mA neons in series giving 7840V 50mA (390VA). 
> Puny -I know.
> Spark gap:
> RQ style cylindrical gap with 5 electrodes spaced as wide
> as possible with a 17W cooling fan.
> RF Ground:
> Three metal rods 65cm in length 1.5cm in diameter 60cm in
> very wet soil. Connected to base of secondary via a 50cm
> long heavy cable.
> And of course a line filter, RF choke, safety fuses.
> BTW line frequency here in Sweden is 50Hz
> While tuning I've been getting the longest spark using a
> metall ball, 2cm in diameter, as a discharge terminal. With
> this the coil tunes at 15 1/4 turns. I also tried using a
> 7.5cm sphere which reduced the spark length considerably.
> This seems very strange to me since I've calculated the
> inductance of the primary coil to about 57.5uH. With
> 0.022uF of capacitance this should give a frequency of
> about 142kHz. 
> 141kHz for a 2cm sphere?!!
> That can't be right.
> What's going on here? 
> Is there something wrong with my calculations?
> Maybe the the input power is too low to produce long sparks
> from larger discharge terminals.
> Hope someone can help me out here.
> Cheers, 
> Erik.