Re: Sync Gap Timing (was Triggered Gaps)

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

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

In a message dated 11/16/02 11:08:38 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

Bill,

There's a delay in charging the cap to a sufficient voltage because
the cap takes time to charge.  This delay depends on a number
of factors.  For this reason, the phase must be adjusted for best
spark output.  Sometimes the proper phase adjustment is near
the trough of the incoming AC, but not all the time.

There is another factor to consider however.  Some combos of
NST and cap value produce strong sparks at two different phase
settings.  One of these settings will be a voltage reversal setting,
in which the voltage will rise then switch polarity and only then
will the gap fire.  This setting gives a terrible power factor and
can destroy the NST due to heat and/or over-volting.  To avoid
this setting, simply check the input current to the NST at both
settings, and use the setting which gives the lowest input current.
Or you can monitor the charging waveform on a scope.  I use a
high voltage probe for this, but one must be careful.

Often, a larger cap value will improve the situation if
the coil gives longer sparks at the voltage reversal phase setting.

John


>This has been asked before, but it keeps coming up, and always bugs me:
>Do you want the gap to fire at the AC peaks and troughs, or at the zero
>crossings?
>
>Seems to me you would want it at the zero crossings.  Between two zero
>crossings, there is a rising, then falling, but always positive (or
>negative) charge being applied.  Between a peak and a trough, there is a
>positive then negative charge applied, cancelling each other.  No?
>
>(I'm assuming 120 bps)
>
>     -  Bill  V.
>