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Re: The Next Coil




From: 	Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: 	Wednesday, July 30, 1997 3:32 PM
To: 	Tesla List
Subject: 	Re: The Next Coil

Bert Hickman wrote:


> Best of luck on the new coil! And I thought your current coil was
> awesome...! I must have missed your experiments with adding 100pf of
> lumped C to increase streamer propagation  - could you describe them a
> bit more? And what did you used for a capacitor??


As part of a quickie experiment, I wanted to add C to the coil without 
affecting the breakout voltage of the toroid.  After rooting around in 
the junk boxes for awhile I found a bag of big doorknob-style caps out of 
a laser power supply.  I stacked twenty of these capacitors, each one 
rated at 2200pF -at-30kV, using threaded 3" standoffs between them.  The 
finished stack, which measured about 10' in length, was then placed inside 
of the secondary along the center axis.
Each cap had a 10Mohm stick resistor in parallel.

After retuning the coil (and increasing Cpri by ~10% BTW), the arcs seemed
to be about 5' longer, but the most noticable difference was the greatly
increased number of ground strikes.  But how much of this improvement was
due to the 10% increase in Epri?

I then ran the coil w/o the sec cap stack but with the same Cpri (and Epri), 
and shunted some of the primary to achieve tuning.  The performance fell
back to about the original level.

As a result the next coil will have a much larger Ctop, but only a modest 
increase in the breakout voltage rating, as it appears the the larger C, and 
not the higher breakout voltage, is the secret to the success of bigger toroids.


-GL