Re: Desktop Bipolar Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>

Hi Dave,

An MMC would be the route to take. 25 inch spark length may not be a good 
estimate, as John's equation is empirical and derived from the classic 
Tesla Coil configuration. I'm personally guessing with the coil unchanged, 
a spark length between 13 and 18 inches.

Regarding a spark gap, I think a simple air-cooled static gap (RQ/TCBOR 
style) would be the route to take. Given the 0.025uF size cap and the 
low-current/low voltage NST, charging this cap with this supply takes time 
(31.25ms). An RSG here is difficult (i.e., say SRSG at 120 BPS would result 
in the cap firing at 7.8KV peak, instead of the desired 10.6KV peak. A 
static gap however with 1/2 inch diameter pipe electrodes and a total gap 
spacing of approx. 0.17 inch would allow the cap to charge near 10.4KV 
peak. Of course, the firing rate will only be 33 BPS. Just some things to 
consider if you haven't yet.

Take care,
Bart

Tesla list wrote:

>Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><dave-at-kyleusa-dot-com>
>
>Hi John,
>
>Thanks for the very cool picture; it will no doubt provide me additional
>inspiration. It is very similar to what I have in mind though I plan to use
>modern materials.
>
>But why a required transformer mod and $500 Maxwell cap? Based on the John
>Freau's equation a 7.5KV -at- 30 could yield as much as 25.5 inches with a 120
>volt input. 18 inches would then seem to be very much in reach. Are you also
>saying an MMC will not work in this application?
>
>Dave
>
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Thursday, June 26, 2003 9:07 AM
>To: tesla-at-pupman-dot-com
>Subject: RE: Desktop Bipolar Coil
>
>Original poster: "John H. Couture by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
>
>
>Dave -
>
>Click on
>
>     http://www.mgte-dot-com/tesla/tesla1.htm
>
>for a bipolar TC coil with 7.5KV/30ma NST. This coil was an antique with a
>Litz wire secondary but regular magnet wire will work as well. To get an 18"
>spark the TC will have to be optimized by rebuilding the NST and using a
>$500 Maxwell capacitor!
>
>John Couture
>
>-----------------------------------
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Thursday, June 26, 2003 12:43 AM
>To: tesla-at-pupman-dot-com
>Subject: Desktop Bipolar Coil
>
>
>Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><dave-at-kyleusa-dot-com>
>
>I have some extra parts and was thinking of a small coil project that could
>be run without grounds and counter poises. I also wanted something that
>could be potentially run in the house with less risk to all the electronic
>appliances.
>
>A bipolar arrangement seems the logical choice. Rather than the popular twin
>arrangement I am looking at a single horizontal coil and thought it best to
>seek some advice.
>
>Some initial design thoughts:
>
>24 x 3.25 inch secondary wound with 30 gauge wire (2,O00 turns)
>A classic 12 inch helical primary centered on the secondary
>Propeller style SRSG
>.025uf MMC LTR
>7.5KV at 30ma nst
>Raised 6 inch spheres on ether end of the coil provide a fixed 18 inch gap
>
>I have run the numbers and they look promising. I expect it to make sparks
>that will easily jump the 18 gap. Worse case I could always throw a 9KV nst
>at it if the output was disappointing.
>
>The number of turns on the secondary seems high but when thought of as two
>separate coils is about right. Is my thinking here correct?
>
>Your thoughts and comments would be most appreciated.
>
>Dave
>
>
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>
>
>
>