Kerry,
Never thought to ask you if you had mounted your spark gap on wood. Yup, relying on the natural insulation properties of any kind of wood product to effectively stand off the HV RF currents produced in the primary circuit of a SG driven Tesla coil is a big no-no! Wood is notorious for carbon tracking even when it may appear to be a non-conductor upon initial exposure to high voltage. And as Deano mentioned, with plywood, it may very well have carbon tracked through one of the internal ply layers where you could not see it. Plastic high density polyethylene cutting board or PVC pipe is often a material of choice for mounting the high voltage energized components of a Tesla coil. Keep in mind that the plastic HD polyethylene would also need a way to manage heat produced from the SG electrodes. Also, I have experienced PVC gradually deteriorating to becoming electrically conductive due to constant exposure to the UV radiation generated by the spark of the SG itself.
Glad to hear that the shock that you got from the NST wasn't too severe. Be sure to let this be a learning experience for you, as if you progress to larger and more powerful coils, the required higher powered transformer will not be nearly so forgiving if you take another "shock"!
Spark safely,David
On Sunday, May 10, 2015 3:37 PM, deano <deano@xxxxxxxxxxxxxxxx> wrote:
On Sun, 10 May 2015 03:45:36 +0000
Kerry Soileau <kerrys@xxxxxxxxxxxxxx> wrote:
> So the only conclusion I can come to is that somehow
> the metal brackets were shorting the circuit out through the wood??.
Sounds likely. Wood likes to carbon track. Plywood may have made a
carbon track between the plys where you can not see it.
> Still have the caps in series( all 17 of them) and I have 20
> more coming Monday. I'll make a bigger MMC with a series parallel
> configuration but having an issue with matching caps to my nst. My
> nst is at 0.0066 uF and if I did 21 caps in series of just 1 string
> that would give me a value of .0068. But problem is I've heard that
> you should and shouldn't match caps to transformer. Not sure which
> way to go on that. Any suggestions welcome and appreciated.
Two series strings of 18 caps paralleled would give you ~16 nanoFarad.
If you parallel your 12/30 NSTs for 12/60 that would be a pretty close
match for LTR for a static gap.
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