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TT-32 coil (proposed plan) and toroid availability



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

Hello all,

I was thinking about a design for a smaller version of my TT-42 
coil.  This smaller coil would perhaps give 32" sparks, and run
off of a 7.5kV, 30ma NST.  Here's the specs, with comments:

Spark length     30" to 32"
Toroid              3" x 10" smooth  (or 4" x 10" corregated)
Secondary       3.25" x 15",  975 turns of 28awg (see below)
Primary          Flat,  8 turns, tapped at 7.5, 12awg stranded
                       pvc ins., close-wound (see below)
Cap            0.03uF  LTR    (MMC)   (see below)
Gap           sync, 120 bps, use PC board for 3" rotor with 1/8" 
                   electrode screws,  1/50 HP  motor, 1800 rpm
Variac       0 - 140V  output.

I didn't bother checking to see if the # of primary turns is correct.
I recommend that anyone attempting to build this coil, use
one of the available computer programs such as Bart's Java TC,
or J Couture's program to verify the tune point

The efficiency of this coil may be a little lower than my TT-42
coil due to the lower NST voltage and fewer turns on pri and sec.
It may be helpful to use 30awg wire on the secondary and use
more primary turns, but I'm not sure how much difference it may
make.  A triggered gap could be used if anyone wants to try that.
I made the cap only 1.5x the matched size to help keep the
voltage a little higher since it's a 7.5kV NST.  A 15kV, 15ma
NST may be better maybe if it can be found, but the cap 
would need to be smaller and the primary would need more
turns.  The sync gap does not have to be very large for this
low powered work.

The original TT-42 coil and gap can be seen at my website at:

    http://hometown.aol-dot-com/futuret/page3.html

[note]...  I now have small 1.75" x 6" spun aluminum toroids
available as per my recent posting.  These are $35 each, I pay
the shipping within the U.S.  Send check, MO, or PayPal to:

John Freau
49 Thiem Ave
Rochelle Pk,  NJ   07662