Re: Output Voltage vs. Firing Rate (fwd)
---------- Forwarded message ----------
Date: Fri, 7 Aug 1998 09:22:23 EDT
Subject: Re: Output Voltage vs. Firing Rate (fwd)
In a message dated 98-08-07 00:15:10 EDT, you write:
> With reference to my desire to try a sync-RSG, am I limited to 2 x Fmains,
> ie. with our 50Hz supply aiming for alignment at respective peak/trough at
> 100 bps ?
> Has anyone tried 4F, aiming for the shoulders & trying to get 2 pulses per
> AC half-cycle ?
I've tried 2x, 4x, 6x, and 8x mains with a sync gap. I got the best results
using 2x mains. But, if the capacitor is too small, then 4x, 6x, or 8x, mains
will work better...but, in my view, not as well as at 2x mains *with* the
larger (proper) sized capacitor. In other words, the break rate that will
work best, will depend on the capacitor size, but I like to select a
capacitor that is large enough so it can barely charge (just in time) at
2x mains. I've obtained the best overall efficiencies in my coils using
lower break rates
If the sync break rate is too high, some of the electrode presentations
may not actually fire (too far from peak...and low on the ac sine wave..
voltage is too low), so the actual break rate will be lower than
calculated. This effect of course occurs with non-sync gaps too.
To ensure that the sync gap *does* fire at every presentation,
I bunched the electrodes closer together (two bunches for a 3600
rpm system at 60Hz mains), so they were sure to fire. This way,
all the presentions occur nearer to the peak where the voltage is
high enough to fire.
A non sync gap with a 600 BPS calculated firing rate may have an
actual firing rate of 400 BPS or so.
A sync gap TC requires a more careful balance between break rate,
cap size, and toroid size, than a non-sync or static gap TC. This is
because in the non-sync or static system, the break rate can be
changed to compensate for mismatches.
IMO, there's not much benefit to using a sync gap at higher break
rates. If you want a high break rate, you might as well use a non-
sync gap, it will give better flexibility and just as good results. It's
within the low break rate domain, that the magic of the sync gap is
realized (but only within a properly balanced system using resonant
charging, a cap size that barely charges in the available time, and a
toroid sized to give only one or two streamers). If a sync gap is just
plunked into the typical static or non-sync TC, without considering
the system's balance...there's a good chance the coil's performance
may degrade rather than improve. Yet, with a proper balance of
components and parameters, the use of a sync gap can improve the
performance of most coils.
> For those of you able to measure such things, what sort of gap firing
> frequencies do you see in well quenched static gaps with NST's ?
> (I appreciate there are *many* variables here, just ball-park rates for
I'd have to check my notes for general guidelines. But it depends on
the size of the cap, the current available,and the gap spacing.