Ben,

Bigger caps are better, at least in terms of stored energy. The resistor values aren't too critical, they must be large with respect to the resistance of the discharge in the gaps. Higher values (100s of k to several M) are fine, but will limit the charging rate. If you can model the spark discharges you could optimise the values. Inductors are also an option, as the discharge is very brief and its risetime so short that fairly small inductor values can offer a large enough reactance.

A Neon Sign Transformer can be rectified to charge a Marx generator. You can also use a flyback supply from a CRT. Running the generator from DC is the easiest, and is almost mandatory for a resistive charging system. It is possible to charge a Marx generator from AC, as long as its charging time constant is sufficiently short, using chokes instead of resistors could make that practical.

Try starting with 1 Meg resistors and the current caps you have. Once you get it roughly working you can improve it from there.

Regards,

Alan

HI

Very cool site i have been trying to make a marx generator for ages but never found the time . I hnow have a box of 20 100pF 20 Kv High Voltage Ceramic Disc capacitor could i use these to make a marx generator and of so would a 10KV NST be ok to charge them and what value resistors shoud i use inbetween the caps. If this wont work what are the best values to use on the capacitors in a marke generator and how do you know what resistors to use

Thanks

Ben