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Re: noob question
Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
This sounds like a good coil design and should not be giving you
1) a defective cap (quicktest --- try a substitution cap
2) xmfr dying --- no xmfr protection circuit (try a substitution
xmfr and be sure to use a "Terry filter" to protect it.
3) not using a "scrap wire" test primary, ie, the # turns required is
slightly beyond what you have available.
At this current 4-5 series gaps with a 80-100 CFM blower fan should
provide good cooling and spark quenching (spark shutoff so the sec
can ring freely around its resonance point without kicking energy
back into the pri circuit).
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
Sent: Tuesday, February 28, 2006 1:10 PM
Subject: Re: noob question
Original poster: ben eells <squeels2171@xxxxxxxxx>
I am using a 6.5Kv 20 mA transformer and a .005mfd 10Kv AC
polypropylene capacitor. My primary coil is 1/4" copper tubing
spaced 1/4" between turns for a total of 15 or 16 turns My secondary
is approximately 1100 turns of 26AWG magnet wire around 3.5 OD PVC
pipe. My top load is an 8" x 2" aluminum toroid. My stated problem
was worse when I was using one spark gap but I have recently
switched to 4 gaps in series. This helps the problem as well as
gives me longer streamers but it doesn't fix the problem. When I
replaced the capacitor the first time the coil returned to full
operation. I suspect it is the capacitor although it's been
mentioned by another person in the list that it could be a ground
problem. I am in the process of building a MMC based on the
capacitance recomended by the tesla map program, around 10.8nf by
using .0176uf 1500V polypropylene caps ran 8 strings of 13 caps in
series. I tried to be as detailed as possible this time. Let me know
if you need to know anything else. Thanks for your help and happy coiling.
Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: Vardan
At 11:10 AM 2/27/2006, you wrote:
>I've been looking for quite a while to find an answer to this
>question and haven't had any luck. Please don't flame me too bad.
We won't :-)
>I've built my first coil based on the schematic for the 12" spark
>coil from information unlimited.
I have never seen this schematic and don't know anything about this
coil. Can you give more detail on it so we know what is going
on. There are thousands of different coils, so we can't say anything
specific without knowing which one it is.
>I can run my coil for maybe 20 seconds or so (depending on the width
>of my gap) but eventually the spark gap stops firing and the coil
>stops working and won't start again until I turn it off and back on
>again. I've tried shortening the spark gap but the problem will
>persist and the more I try to run the coil the sooner the gap stops
>firing. Can anyone explain to me why this happens and what can be
>done to keep the coil running while the power is on. The only
>explaination I have been able to come up with by myself is that my
>capacitor is slowly dieing (I've had to replace the capacitor once
>already) and the longer I run it it can't produce the breakdown voltage.
Did replacing the capacitor restore the coil to full operation
(temporarily)? If so, it sure sounds like the cap is burning up. If
we know more about the coil, we can find a cap that won't die.
It could also be the gap gettin g dirty, but simply cleaning the
electrodes would fix that. My guess right now is that the cap is not
able to withstand the coil. An MMC should fix that easily but we
would have to known the voltage and value and something about the
coil especially the type of transformer running it.
I have also seen arcing inside the secondary do this, but that makes
smoke and such.