High Voltage Coupling

[diyfella]

I have a tiny hv transformer around 10 to 20 kv that i drive using a function generator and a mosfet. It works fine and generates a nice and stable arc in the output. I wanna couple the hv output to another circuit basically the same as a tig hf start circuit. In tig welders this is normally done with a flyback, a spark gap, a hv cap and coupling coil like these





but no matter how hard i try i can't get the hv output to be inducted to another wire.
also when i add a hv cap to the output in parallel it doesn't arc anymore.

this guy has done the same thing but he uses a very powerful flyback transformer with a zvs driver where as mine is a tiny epoxy transformer the kind you find in a taser (without voltage multiplier or rectifier).

[David Hess]

In tig welders this is normally done with a flyback, a spark gap, a hv cap and coupling coil like these

Did you include the capacitor and spark gap?  The flyback transformer output is not enough to directly drive the coupling coil.

I actually did not know how the HV start on a TIG works until you listed the elements.  Now it is obvious.

[diyfella]

Yes, i tried all that but to no avail.

[David Hess]

Yes, i tried all that but to no avail.

Is your spark gap triggering?  A lower power flyback circuit should result in the spark gap triggering at a lower frequency.  If it is not triggering, then the voltage is not high enough, or the spark gap is too large.

[diyfella]

Yeah the spark gap is sparking, but when i put a hv cap in parallel to the output no more arc. even with just the cap in the output it no longer arcs.