My experience so far in producing a high voltage high frequency spike wave pulse has been very slow as there is much misinformation on the net.Evan The author of this page
First forget your tv flyback monitor transformer ,they die very easily if overloaded.
Get yourself an oil filled car ignition coil cut the case off and pull out the iron core,
Then place in glass jar and top up with some oil.
Heavily insulate the terminals.
You donít need a ferrite core ,but drop one in if you must.
The higher the frequency the lower the spark output from the High tension output.
Start with 50 volt VPP on T2 and 12 volt or less on T1 primary.
VPP on T1 is constant 50-120 on T2. I ran mine successfully on four 4 car batteries for a while.
Critical point is transformer T1 all tvís have this small transformer about 30mm by 30 mm,it is there to protect your frequency generator ( a Modified Dick Smith kit Australian hobby components supplier costing approx $50 )
The other main point are diodes 2 and diode 3 must be strong enough to withstand the high voltage discharges, put a dozen high speed diodes in if you canít get the real thing.
This circuit does decompose water at 50 volt T2 primary on an car ignition coil at about fifteen thousand pulses per second.
I could not see much of a difference in gas production on carbon electrodes from 1000 to 15000 pulses per second.
I suspect the voltage was too low.
The capacitor after diode 2 and diode three probably the secret to get spike wave.
POINTS TO REMEMBER,
(1) Function generator must output same voltage no matter what frequency.
(2) The use of an oscilloscope is essential, never use a frequency counter they tend to give false readings if your wave form breaks down at high speed.
Eg it does happen be warned.
(3) High voltage resistor 300*1 to measure High tension, work out the frequency from off the scope its apparently real easy.
(4) Cheap mosfets $8 from Dick Smithís Electronics have a slow action, but you need the $80 for the real ones if you dare.
(5) T1 essential as well as the diodes 2 and 3
(6) Take out the iron core from coil and then rewind primary with thicker gauge wire if your confident of doing it correctly.
The circuit in full