Tesla coil not working (help anyone?)

[TungstenTesla]

Hi All,

Long time reader, first time poster. I'm currently building a tesla coil. here are the details:

1.) I'm using three parallel NSTs that each output about 6500 volts at .9 amps.

2.) I'm using 4 high voltage capacitors that I built using two sheets of aluminum siding with polypropylene as a dielectric between them. They are held together with a PVC ring, and submerged in mineral oil inside a 4" pvc tube. There are 4 of these. I've tested them with my multimeter and they are not showing any current flow between the two leads so they should be ok.

3.) my spark gap is made from tungsten carbide held by mig welding tips (copper) threaded onto 6 gauge copper wire.

4.) my primary coild and secondary coil are in good shape, and for a topload I have a sphere and a tauroid.

I haven't been able to get it to work. When I connect the NSTs to the spark gap, it fires fine. but with I hook up the capacitor bank and the primary coil to the spark gap, the gap doesn't fire and there is no discharge. who can help me troubleshoot this? I would be most appreciative!

 

[Bob S]

How about posting a sketch of your circuit. Do you basically charge your capacitor in half a line cycle, and discharge it into the primary of your coil transformer through the spark gap at 60 Hz? Or do you have rectifier diodes? Do you trigger the spark gap, or just let it break down when the voltage is high enough? When you charge the capacitor, is the high side tied to one side of the spark gap and the other side grounded, and when the spark gap is triggered, it essentially grounds the high side of the capacitor, and pulses current through the primary coil?

What do you think the capacitance is? Using I = C dV/dt. what do you think I and dV/dt are? Theoretically, I_max ~2.7 amps, and dV/dt_max = ~377·6500 = 2.5 x 10⁶ volts/sec, implying an optimum capacitor is ~2.7/2.5 x 10⁶ = 1 uF. Is that correct?

What do you see happening when the room is totally dark?

Bob S