Re: New Coil/RSG Annoyance

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 4/17/02 8:23:14 PM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:


>
> Hi John, All.
>
>     I had no idea those xfmrs could push out 9 feet!  I must be doing
> something horribly wrong in that case.  I had to resort to my old vacuum
> gap to get what sparks I got.  The sparks were much brighter than they
> were on my big coil, probably due to the smaller cap (0.075uF as opposed
> to 0.1uF) and higher breakrate.



Winston,

If you're just using the 2 transformers in series without a
voltage doubler circuit, then you don't really need to use LTR,
I don't think.

Since the voltage is rather low from those transformers, then
resonant operation is OK.  I think folks usually use up to
0.08uF or so at 120 bps.  Alan Jones has done a good job
of optimizing the design, and has gotten sparks of about
9 feet, at 120 bps.  

To acheive long sparks you'll need a larger secondary.
With the 19" tall secondary, you'll be limited to about 50" sparks
at 120 bps.  Polyester caps will cost you about 10% or so in
spark length.  These are all ballpark figures I just gave.

Cheers,
John


>
>     The reason I tried running at 240 BPS was due A) the small cap and B)
> the difficulty I've had trying to at 120 BPS.  Besides, wouldn't I need
> an LTR cap to make 120 BPS a viable break rate?  Resonant size for my
> PSU is 0.1 uF, and I really don't see myself with the $$$ for a 0.15 uF
> cap :-(.
>
>     I know this is a vaque question, but is there anything else obviously
> wrong with my coil?  How far can I push my little 4" secondary?  It's
> already done better than my larger 6" secondary in the racing spark
> deptartment ;-(.
>
> Specs:
>
> Secondary- 40mH, 19" tall with about 1300 turns of 28 AWG
> Toroid- 22pF 6" by 20"
> Primary- Flat spiral 3.125 ID, 0.5" C-C spacing, tapped at turn 7 (best
> spark).
> Sparkgap- Single vacuum gap (would use rotary, if I could get it to fire
> right)
> Cap- 0.075 uF polyester dielectric (lossy I know, but it's all I have
> right now).
> Coupling- ??? (Not high enough for racing sparks, though).
>
> Thanks,
> Winston
>