Re: neons & rsg
From: Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
Sent: Monday, August 04, 1997 11:59 AM
Subject: Re: neons & rsg
>> I know many have said not to use rotary gaps with neon xformrs.
>>What is the theory behind this? Could you use a rsg with a neon if you
>> use protective chokes on the neon outputs?
>If the optimum capacitor size is used for a particular neon xformer,
>gap will only be able to fire once per half cycle. Whenever a gap
>once per half cycle, it's best to fire at the peak. Using a fixed
>gap, firing will occur near the peak, but with a rotary, the firing may
>attempt to occur "anywhere" along the half cycle. If the gap presents
>too soon, while the voltage is still too low, it will not fire. Thus
>may not fire at all on that half cycle and may wait until the next half
>cycle to fire. Due to resonant charging effects, the cap will be
>to an extra high voltage if this occurs, and this will stress the
>It is also possible that the irregular firing of a non-sync rotary
>occasional voltage resonant spikes which can damage the transformer.
>Another way to look at all this is that a fixed gap LIMITS the firing
>voltage, whereas a rotary does not.
>If a synchronous rotary is used, the situation is changed for the
>The synchronous rotary will fire at the same place at every half cycle,
>and will not skip a firing, thus the voltage will not rise as high as
>half cycle was skipped. Sync-gaps work very well with neon trannies,
>and I suspect that they can outperform a regular static gap. I have
>never blown out a neon tranny while using a sync-gap and I do not
>use any chokes...but i do use a safety gap.
>Some people do use non-sync rotaries on their coils, and obtain
>reasonable results, but YES it is probably important to use chokes,
>safety gaps, and perhaps even current limiting resistors in series
>with the chokes. The wrong sized chokes can make the situation
>Interestingly, a non-sync rotary will not be any better than a static
>gap towards producing spark output length...unless perhaps you
>have paralleled quite a few neon trannies so that the power input
>is high, and the superior quenching abilities of the rotary are called
John, Thanks for the info.
I think I will try and build a synch gap. But I don't understand what
makes a synchronous gap to be synchronous. How could one be assured that
it would always fire at the right time? My coil right know is using two
12,500v 30mA neons (60mA total) and the primary resonates at about
Thanks again for the help.
Tristan Stewart, CET
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