Hello ,
I've just received an e-mail from S1R . He said he will make another video of the entire set up together.(working circuit)

HV

Hi Luc

Thanks for the welcome.

I was looking at the circuit and it struck me I *think* the idea behind the switch is to act as a flip-flop between charging the cap when switch is in one position, then discharging into the spark plug when in other position.

Presumably a couple of decent size FETs might do the same job, but they would have to be big ones. I have seen 169 Amp ( 680 Amp pulse peak ) 55VDC rated FETs for automotive applications
( they are IRF1405 ) . Presumably you could alternate their on periods so when one FET is on and charging the cap, the other is off, then swap to discharge into spark plug.

But as were dealing with 300-400VDC, you might need larger FETs like those used for DC motor control for say trams and other large DC motors....

PS- just ordered an second hand 4 stroke pump motor to try all this on......this is the best bit.
PPS - 50 KV doesnt tickle......

Cheers

Steve

@plasmastudent

I hope the engine you bought has a negative chassis and therefore +ve from the coil.  Alot of small engines work with the HV current flowing in the opposite direction making it near impossible to protect the coil from the 400v power supply.

The problem i am having at the moment is the capacitors in my voltage doubler,  the caps blow if the coil isnt allowing it to discharge via the spark/plasma gap.  IF i spray too much water on the plug, it stops the firing and the capacitors blow.  I am in the process of making a way to get 400vdc+ without using capacitors.

I had thought to use a 240/480 transformer and a full wave bridge rectifier.   However these transformers are not cheap or readily available.
My second thought was to somehow modify the inverter to output higher than 240vac to begin with, for this however i have no idea.

Can anybody help me on this? Once i can sort out a safe and reliable method of supplying 400+vdc to my spark plug i can put the system into a test vehicle.

Check out this clip we should look into Electric Taser circuit.
in this video clip there's a salt water explosion with Taser.

i think it's worth a look.

http://uk.youtube.com/watch?v=Qm_KMMK7-XQ

Another way to generate HV http://wiki.4hv.org/index.php/Flyback
A lot of videos on Youtube as well, type ZVS Driver into the search bar.

Only experienced electronic constructors should attempt this!
High level of shock risk!