Re: Low output coil

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi John,

While messing around with your specs, the cap bank is the confusing. I 
stopped until you can clarify. I can easily see your primary will need to 
be in the range of a 0.15uF (+/- 0.01). But your specs state 5 caps per 
string and 25 strings in parallel (at least that's how I understand it). 
The trouble I have is you individual cap value. On one line you say it's 
0.01uF and on another line you say it's 0.05uF?

With 0.01uF for the individual cap size, you'll want 8 strings (5 per 
string). Total capacitance is then 0.016uF.
WIth 0.05uF for the individual cap size, you'll want 3 strings (10 per 
string). Total capacitance is then 0.015uF.

Could you clarify your cap bank (a cap measurement is the best confirmation 
if possible).
Take care,
Bart

PS: For 900 turns of 24 awg, I suspect your coil is wider than 3" or longer 
than 18" (or your wire size is more like 25 awg). 900 turns of 24 awg would 
be difficult to fit in the range provided for standard single build insulation.

Tesla list wrote:

>Original poster: John <fireba8104-at-yahoo-dot-com>
>Hello,
>I've just completed a 2kw Tesla coil with the help and suggestions of 
>members of this list namely Gerry R and Ed Sonderman, thanks again guys. 
>The reason for this E-mail is that it has a very low output, about  3" it 
>should produce streamers about 36" at least. The coil is in tune judging 
>from spark length and oscilloscope measurements. My personal thoughts are 
>it might be K but I'm new to this. Dose anyone have suggestions, any are 
>welcome.
>Specs:
>Transformer
>120v 60Hz
>2 Mots stacked for 4800vac
>secondaries connected to core- cores grounded
>2400vac relative to ground
>PFC
>No filter
>
>
>   Spark Gap
>Adjustable single half ball gap with fan (65CFM airflow)
>I think I'll try to build a sync gap
>
>Tank Cap
>MMC Type
>5 in series 25 in parallel 125 total
>Each cap 0.01uF 3KV
>0.05 uF 20% tolerance each cap
>Rated 15000 VDC
>Made from ceramic High Q caps
>Cap bank has been checked for damage by visual a multimeter inspection-
>not
>damaged
>
>Primary
>Type- Flat "pancake" coil
>7 turns
>1/4 inch copper tubing
>1/2 spacing between turns
>1 inch spacing between inner most turn and secondary
>4 inch width of coil
>3/4 of an inch from base
>3.81 uh need to form resonant freq of 363kHz
>14.051uh total -formals used
>Strike rail - open loop, 4inches above primary connected to bottom of
>secondary
>
>Secondary
>aspect ratio of 6:1
>3"! inch by 18 inch
>#24 enameled magnet wire
>about 900 turns
>Top load- toroid 16.117pF
>resonant feq at 363kHz with top load -measured
>1/4 inch above primary
>Top load close to secondary for electrostatic shielding - see I do know
>something
>wound on power line grounding insulator
>
>
>
>