Re: Alterations worth doing?

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Tom,

Your first design with 22nf was a resonant design (Cres = 23 nf).  The BPS
must have been very high.  With your second design, the Cp of 35 nf will be
very close to 1.6*Cres (37 nf) which should be a good choice for a static
gap.  You are however making two changes, so the difference between the two
coils will be harder to see.  You might try the new coil with the original
22nf first leaving the spark gap setting at your original setting.

Gerry R.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, July 19, 2004 6:39 PM
Subject: Alterations worth doing?


 > Original poster: "Tom Luttrell PWRCOM" <tom-at-pwrcom-dot-com.au>
 >
 > I dropped my secondary coil on a sharp edge and irretrievably stuffed it!
 >
 > Since flattening the primary (was 30° conical) and raising the secondary
up
 > ~2" this coil has performed brilliantly (~1m arcs for 880VA in).
 >
 > However the need to rewind the secondary led me to wonder if the following
 > modifications were worth doing.
 >
 > Current design:
 > ===============
 > ~760t of 0.9mm (150mm dia x 680mm tall, 4.53:1 h:d) secondary
 >
 > 22nF 27kV MMC resonant with 11kV 80mA NST (50Hz)
 >
 > Primary tap point = 8t
 >
 >
 > Planned design:
 > ===============
 > ~1200t of 0.6mm (155mm dia x 700mm tall, 4.51:1 h:d) secondary
 >
 > 35nF 27kV LTR MMC (same NST)
 >
 > Estimated primary tap point = 8t
 >
 >
 > So by winding more turns with smaller gauge wire and balancing this with
an
 > LTR primary cap I get about the same primary tap point and hopefully will
 > not need to alter the primary winding copper tube at all (I only have 2
 > extra turns, for a total of 10t available).
 >
 > The original reason for so few turns in the secondary was to reduce the
 > resistive RF losses by using large gauge wire. It will be interesting to
 > see how the two coils compare.
 >
 > I was not ever worried about my NST overvolting (resonant kick) as the
 > static gap is not too wide and in parallel with the NST. However seeing if
 > the extra energy available from the LTR cap is worth while should be
 > interesting.
 >
 > So far every modification I have made to my original design has brought my
 > coil closer to the accepted practical design rules touted on this list -
 > with excellent results - and these last two modifications should make an
 > interesting comparison.
 >
 > Tom.
 >
 >