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12kV, 30ma NST TC specs (42" sparks)



To all newbies,

I've been getting more requests again for the specs for my TC, so I
figured I'd post this again on the list.  This coil was designed to obtain
the maximum possible spark length from a 12kV, 30ma NST.  A 15kV,
30ma NST was also tested on this coil and gave 45" sparks.  Since
I've posted these specs a few times over the last two years, I'm curious
to hear if anyone has built this coil (other than myself), and what they
thought about the performance if they built it.

<< <<   Here's the specs for my coil:
    
    toroid....5" x 20",   or  4" by 17" corregated,  or 4" by 13" smooth 
    sec......6.5" x 24" , #28 formvar magnet wire, place sec 1.5" above center
        of primary coil.   (or 4" by 23" secondary with same wire)
    pri.......tapped at 34 turns of # 12 stranded pvc ins. wire close wound,
         (tapped at 20 turns if the smaller secondary is used), flattish 
         inverted cone, 15% angle.  
    hook-up wire....# 12 stranded or solid
    cap...  0.0077uF, at 45VAC polypropylene  (or 0.0147uF based on 
        new work.  The larger cap reduces the resonant voltage in the NST,
        and should make it last longer, although I've had no problems with
        using the 0.0077uF cap.)
    sync-rotary gap....120 bps
    transformer....neon sign, 12kV, 30ma, 
    power factor correction cap,  50uF  (optional)
    spark length... 42" max
    safety gaps...attached to NST bushings at each end
    variac...step up type that gives 140 volt, 7.5amp output.
    
    Regards,
    John Freau