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Re: BIG resonance! - thoughts...
In a message dated 99-04-09 05:00:33 EDT, you write:
> How do I know when the tank cap has successfully charged to full voltage?
Jon,
If you use a resonant sized cap, it will charge fully, so you won't have
to measure the voltage. You can use a high voltage probe with a scope
to measure it, but you have to be careful not to get electrocuted or to
kill the scope. There are other clues too. You can set the safety
gaps until they fire, and judge the voltage by the safety gap setting,
that sort of thing. I should mention that using resonant sized caps,
might stress the transformer more than normally. I haven't had any
problems, but some folks on the list prefer to reduce the resonant
charging effects in an attempt to protect the transformer.
> With my main gap at 0.336" it will fire steadily, miss a few firings, then
> continue on with no problem. When it misfires it scares the heck out of me
> as my first thought is that something died. When it misfires it seems as
> though it must miss maybe 10 firings! I would think that the safety gap
> would fire when the main gap misfires, but it doesn't. Am I setting my
> safety gap correctly? I have two gaps to ground, each gap is 0.312". If I
> set the safety to 0.250 once it fires it won't stop.
If the gaps misfire, they're too wide, and can ruin the transformer. I
dont' really like to use static gaps with wide spacings with NST's.
They're just too fragile (the NST's). I prefer to use the sync rotary,
to keep things controlled. I actually use a wider gap than you are
using (if you're using at least 12kV). I use about 7/16" on both sides.
The static gaps really seem to destroy transformers unless the gaps
(main and safety) are kept narrow. Probably safest to stay at .250
for the safety, and narrow the main gap, so the safety gap doesn't
fire. THis will limit spark output and protect the transformer. There
are many other approaches possible however, such as obtain more
transformers, but keep the gaps narrow, so the gaps will fire more
often, and gain some output energy that way.
> My toroid was about 1.5" above the secondary, I lowered it to where it was
> even with the top turn and the turn to turn sparks stopped, but then the
> toroid was much to close to my 15 degree primary and I got lots of strikes
> to the strike rail. I'm now in the process of rebuilding the primary. A
> "pancake" design will give me about 3" more distance to the toroid. Should
> help.
Sounds good. As you go up in power, the whole coil has to get bigger
or breakdown will always be a problem.
> Sounds like there is a sync rotary gap in my future.
The sync rotaries have their advantages. Some folks like them, some
don't. You may want to read the "2 resonances" thread on the list
too. I plan to do some more tests using NST's.
John Freau
> Jon Rosenstiel >>