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Re: Testing Caps
From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: Thursday, November 27, 1997 1:35 PM
To: Tesla List
Cc: megavolt-at-usa-dot-net
Subject: Re: Testing Caps
Matthew,
Bert Hickman answered some of your questions, so I will not comment
on the parts he already answered.
If you run your caps without a primary/secondary set attached,
you will give the caps a beating. Resonant rise will go
unhampered, and the neons and caps may easily be destroyed.
Lots of new coilers are totally unaware of the resonant rise
effects that arise between the transformer and the caps.
In resonant rise the caps can rise up to a voltage several times
that of the transformer's PEAK voltage rating. One list repondent
recently told of using bottle caps and neons and getting
sparks that ran the length of his high voltage insulators. This
is one of the surest ways I know of to destroy. your transformer!!!
If you want to "test" the caps, place a safety gap across the
neons first. But I don't recommend running anything less than
a complete Tesla coil. Without a primary you have no primary
inductance to reduce the initial surge current. That will result
in sparks at the main gap that are excessively hot and noisey.
It also means that the caps will try to dump EXCESSIVE currents
and then you are just begging for cap destruction. When I say
the caps take a *BEATING*, I mean that literally. Please don't
do this to your caps! With bottle caps you could run the risk
of exploding glass bottles. You would be causing the poor
glass dielectric to fracture from the physical shock wave that
you would be generating in the glass dielectric. This kind of
destruction would be rather immediate and of a catastrophic
nature. If you didn't experience immediate destruction, then
you could count on a delayed destruction as you continued
to apply power. The heating would be most RAPID, especially
with glass, and this would create a thermal gradient that can
fracture the glass.
If you use a primary but no secondary, the situation is not much
better. Again, not recommended, because there is no secondary to
exchange energy to. And again the caps take a beating.
ONLY test using a complete Tesla coil setup. I know that the
tendency is to want to play with the parts you have. But if you
do that you stand a good chance of destroying those parts before
you ever get a Tesla coil going.
Hope this helps.
Fr. Tom McGahee
******** Original post follows
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From: Tesla List <tesla-at-pupman-dot-com>
To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
Subject: Testing Caps
Date: Wednesday, November 26, 1997 8:20 PM
From: Matthew Mills[SMTP:megavolt-at-usa-dot-net]
Reply To: megavolt-at-usa-dot-net
Sent: Wednesday, November 26, 1997 1:01 PM
To: Tesla List
Subject: Testing Caps
Hi, I'm still in the process of building my first coil. I have aquired
2x 15kv 30ma neons and am starting off with saltcaps and vertically
stacked caps, my question is,
Is there a way to see how well the caps work without having them
connected to a coil? (I have wound a secondary but have no primary coil
yet.)
I have got a 15inch high by 10 inch round lidded polyethylene tub which
I am using to test individual salt water capacitor bottles
The bottles I am testing at the moment are 1/2 gallon chemical bottles.
The straight side is 7 inches high, they are 6 inches in diameter and
the glass is 3.5mm thick (approx 1/8inch)
now I tried working out the expected capacitance on paper (very hard)
with no calculator and got around .0017µF which seems low. So 6 bottles
would be .0102µF
Am I right?
Im wanting to see how well these work without frying my neons.
Thanks,
Matt.
PS I havent got a Capacitance meter or a multimeter yet (blew the last
one)
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