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Re: Using sync gaps
Snip.....
>From: FutureT-at-aol-dot-com
>If anyone tries 120 BPS, the cap size must be matched to the
>system, or all bets are off. Folks just drop a sync gap into
>their coil and expect great results. Might happen, might not.
>If the cap's too small, the TC will *need* a high break rate to
>give a reasonable output spark. Since 120 BPS is a low break
>rate, a larger cap is needed to keep the input power the same.
>Then there's the resonant charging aspect. Sync gap TC's
>require more careful designing than other gap types. If you've
>got power to spare, raising the break rate of any 120 BPS TC
>will increase the spark output. This is not the question. The
>question is efficiency.
>
>John Freau
>
>
Hi John,
In my case, nothing else but the gap needed to change. My single 60mA
neon is a non-resonant charged system (the neon's voltage and current are
15kV at 60mA with 120 VAC in charging 20nF of capacitance). It was always
designed to run at 120 BPS My attempts to run with lower value caps and
higher BPS never worked as good as the 120 BPS non-resonant mode (I
probably didn't turn it up high enough :-)). I did put a powerful safety
gap on the neon output but this is more to protect against secondary from
primary strikes which modeling shows is "bad" (I don't use strike rails).
However, with the protection gap, the neon and all will be kept within
their ratings in such an event.
You are very correct in pointing out that if you change from a static to a
sync (or async) gap in a resonant charged system, you must have an
effective safety gap system to protect the neon from over voltage and over
current. If the gap miss-fires, the over voltage will arc at the gap and
in effect provide a load to drain the energy from the rising voltages of
the resonating charging system. If this load were not there, the resonance
could easily charge the system up to several times the normal voltages and
blow the neon, caps, etc.
Terry Fritz