tesla coil spark length

[electronboy]

Im working on a Tesla Coil. I've gotten it to run but i am not getting good sparks. I have an 8 kV 30mA NST as my HV power supply and my capacitor is just a small Leyden Jar. The width that my spark gap fires is about 0.5 mm. My primary is 23 turns of whatever gauge US mains cable is and my secondary is 500 turns of 28 gauge magnet wire. I have achieved sparks that are probably 2mm long at almost perfect resonance. I'm wondering if anyone out there knows how to increase my spark length.

 

[davenn]

easy ... increase the voltage sunstantially !!

there are formula around that will tell you what voltage it takes to jump a certain gap.
do some google searching


cheers
Dave

 

[duke37]

The Tesla types use 3000V/mm I believe.
If the output voltage is not as expected, perhaps there is insulation breakdown inside the gubbins.
Have you got the primary and secondary resonance the same? I would doubt if the coupling is very tight.

 

[electronboy]

does that mean that in an arc , every millimeter
represents 3kv? or is it the electric field?

 

[duke37]

I have not played with super high voltages but, in the case of electric fence energisers, the figure of 3kV/mm seems about right. Surely this is the electric field strength.

Mr Volta would like his name spelt with a capital V.

 

[shrtrnd]

I thought only Jack Kevorkian assisted with suicides of ten-year old boys.

 

[davenn]

I thought only Jack Kevorkian assisted with suicides of ten-year old boys.

hahahaha. Tis another Darwin Award in the making huh

this is seriously dangerous for some of of this age and lack of knowledge to be playing with

cheers
Dave

 

[jackorocko]

I got an old tesla coil I found at an auction. Handheld model, I have no idea about the output voltage but it has a spark length of an inch and I can burn my name in my arm with it. It is actually quite wild... How would one measure such a thing, or is it just a huge circumstantial guess without knowing the specific design criteria?

The coil I have was used in a tv factory is my understanding. They use it to test the tubes to make sure they work before leaving the factory. How true that is I have no idea, but it sounds plausible.