[TCML] Tesla Coil Problem: Capacitors?

[David Dean]

Hi Scott

That NST is solid state, stated output is 6kV at 30mA at 34kHz, 10kV at 30mA 
at 32kHz. It is not intended to be used for anything other than a luminous 
gas tube. You might be able to use it for a Tesla coil if you rectify the 
output, but otherwise it will never charge a capacitor like a 60Hz coil and 
core unit. A single string of 12 1N4007 diodes inserted in series with one of 
the output leads should tell the tale.

later
deano

On Saturday 16 February 2008 04:55:09 am Scott wrote:
> Hey there Telsa List!
> I have been working on my first coil for about 4 months now and I'm almost
> sure it's one issue away from sparks....
> My problem is a little tricky, so I'm gonna be as detailed as possible here
> (sorry for the massive post).
>
> First off:
> The coil is built around a 10kv 30ma neon sign transformer with stupid evil
> GFP: Here's the description from the maker:
> http://www.jcmimports-prostore.net/servlet/Detail?no=2
>
> The spark gap is made of 8 copper electrodes, about 1-2mm spacing between
> each
>
> Primary and seconardy/topload all match and are correct size according to
> the calculators from deepfiredneon:
> http://deepfriedneon.com/tesla_frame0.html
>
> The secondary and strike rail are "grounded" to a large steel spike
> hammered 2 to 3 feet into wet Earth.  The grounding tab on the sign
> transformer is not connected to anything.
>
> When everything is wired according up in a complete circuit and power is
> added, nothing happens.  If the primary connection point is changed,
> nothing.  It the spark gap size is increased or decreased, nothing.  What
> gets interesting is when the circuit is slightly broken at some point (an
> ark is drawn between any 2 components) it either fights to keep current
> running through the cap-primary loop, or if that is impossible, it just
> completes the circuit through the spark gap, ignoring the primary loop.  It
> won't do both actions at once (fire the spark gap while the circuit is
> completed).  I know the primary coil/gap is working because whenever the
> two are connected (with some kind of arc in the loop) a florescent light
> will light up when over the primary.
>
> I'm almost certain the caps are to blame for two reasons: they are not
> breaking down the spark gap when put in the right place in series, and when
> they are removed from the circuit completely, it acts the same way.  I am
> using these caps: http://www.vishay.com/docs/28124/mmkp383.pdf
> (0.047uF at 1600volts, wired as 2 series strings of 12 in parallel (24 caps
> total, overall rating of 0.0078 uF and 19200 volts).  Each cap was tested,
> and it holds its charge under low voltage, and discharges with a spark.  No
> bleed resistors...yet.  The cap bank produces a different ark than the NST
> when arced to the primary coil (a high pitched crackling instead of a low
> hum), but this tone can only be heard at that connection.
>
> Alright, thanks for reading so far.  So what do you guys think is going on?
> How can I test my caps to be sure they work alright?  Do you see an obvious
> problem with another component?  I will check back frequently, so feel free
> to send in ideas or questions.
>
> Thanks a lot guys, now let's get this working!
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