TSG Observations

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

Original poster: "Paul Arrowsmith by way of Terry Fritz <twftesla-at-qwest-dot-net>" <p_t_arrowsmith-at-hotmail-dot-com>

I have just put together a coil and tested it with a TSG with interesting 
results.
The Coil is powered by a 5KV transformer (from a broadcast transmitter?)of 
unknown current capability other than I am sure it can supply a few amps 
more than needed. Using a .075uF MMC which I calculate to be a 1.9 Joules 
bang size. With a simple 2 series static gap I get strong 1 meter (41 
inches) regular sparks with a few longer before the gap over heats.
My clamp meter measures a current  6A from a 240V 50Hz supply,but I am not 
using any PFC so I think I could get that down to about 3A with PFC caps.
I tried a triggered gap using a fan speed controller/ light dimmer but had 
two problems- 1. not enough phase range 2. kept setting of the household 
earth leakage circuit breaker(balanced core circuit breaker), I believe this 
is because being in Australia I cannot obtain a isolated ignition coil and 
used a standard one and some leakage current may be causing a active/ 
neutral imbalance. A mains isolation transformer would fix this.
I built a John Tebbs zero crossover detect circuit into a di-cast box with 
feed thru caps on all inputs and outputs as I expected RF to be a problem 
with it. It looks great on a CRO but the shielding is not enough to stop the 
RF getting into it and causing it to run erratically and false triggering 
all the time when on a TC.
Thought I would go back to the dimmer idea, not having a isolation 
transformer I used my 240V to 110V transformer and found with lower volts 
applied to the dimmer that the correct phase adjustment point was about mid 
way on the pot! Lowering the volts to the dimmer made the phase adjustment 
useful. The earth leakage breaker hung in there too. After a lot of 
tinkering I got the thing running the best I could with the TSG. The sparks 
were about 1M but thin and weak. The basic static gap gives slightly longer 
but much stronger sparks with a lot less noise!
My conclusions from this is (in my case) that lowering the input V to the 
dimmer moves the phase control sweet spot more central in the pot travel. A 
basic static gap gave better results than the TSG.
Has anyone had really impressive results from a TSG?
Maybe I am doing something not quite right?
Any comments welcome.

Paul A (Australia)



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