Original poster: Ed Phillips <evp@xxxxxxxxxxx>
Original poster: "James Howells" <james@xxxxxxxxxxxxxxxxxxxxxxx>
I have spent every day since Jan1 working on my tesla and can not
get more than a 1" spark no matter what I do
To save my sanity - some help is requested - I WANT TO GET BIGGER SPARKS!
Power supply:- Twin Auto Ignition coils - 555 interrupter through
two power transistors. A separate oscillator supply to main 12v
battery-ball point pen case chokes - works well
Spark gap :- 6 mm copper tube fixed end to end but gap adjustable -
best setting seems to be 0.1"
Primary : 4 series 390 pF 15kv caps , and 3 in series 390pf 15kv
caps ( should be 4 of each, but leg fell off one cap and no replacement yet)
the three strings are in parallel
{4 x 390}
{4 x390}
{3x 390}
Primary coil wound on 4.3" plastic soil pipe ( sewer pipe) with
.048" enamelled wire
Turns 18 at present but was 30 and reduced it and tested one turn
at a time down to 18 turns
Secondary: wound on 2.64" dia white ( abs?) plumbing waste pipe
approx 450 turns of .019" enamelled wire to a height of 10.25 "
Various toroid top loads have been tried ... and non , which works best!
The present spark at the Tesla is about 1" which is about 20% of
what I expected
I have not been able to improve on this - PLEASE HELP!"
Haven't seen a response to this so will add my own. I think
your problem is much too small a primary capacitance - not enough
stored energy. I calculate 325 uufd, the resonant frequency of
your secondary as about 1370 kHz without top load, and the primary
circuit resonant frequency at about the same. I have a similar
coil (bit larger, bit lower frequency) which will produce 4"
streamers to a screwdriver held in the hand. Uses an 0.0047 ufd
primary capacitor, single Exel "super coil" driven about as
yours. 2.5 amps at 12 volts input power. Try a lot more
capacitance and adjust the primary accordingly.
Ed