I have not taken more test with coil circuit, But I have build small DC to DC converter for efficient plasma spark generation no need of bulb. circuit is for bike and capable to charge 30uF capacitance at 300Volts.

White spark is not useful it is cold electricity and maximum energy goes into making bright light.
Purple spark gives high temperature.

How to get rid of spark plug eating problem ?
Which insulating material (high temperature) is suitable for making spark plug at home ?

@vlindos
   Put capacitor of same value in series, (instead of mosfet put capacitor) to remove bulb, but you get half voltage across capacitor. MAKE SURE POLARITY

@Cap70,

I have a marine plug like Xbox, "Champion L76V" this is the plug giving purple spark...I'm waiting for caps and I will replicate....

Xbox says the marine plug fires three times faster .....You can make one by cutting the cathode "L" off your plug, then file the center anode level .....they look like they will last alot longer....Did you post the DC-DC circuit ?

Quote from: capacitor70 on August 18, 2008, 12:38:56 AM
I have not taken more test with coil circuit, But I have build small DC to DC converter for efficient plasma spark generation no need of bulb. circuit is for bike and capable to charge 30uF capacitance at 300Volts.

White spark is not useful it is cold electricity and maximum energy goes into making bright light.
Purple spark gives high temperature.

How to get rid of spark plug eating problem ?
Which insulating material (high temperature) is suitable for making spark plug at home ?

@vlindos
   Put capacitor of same value in series, (instead of mosfet put capacitor) to remove bulb, but you get half voltage across capacitor. MAKE SURE POLARITY

Thanks cap70 for the ideas. I would go with them soon after I made the test with 2stoke engine.
At the moment the capacitor charging seems to be fast and accurate enough. See my video: http://uk.youtube.com/watch?v=kVXKF_7ALNg

Btw there's no spark plug eating at my setup - how much time spark was running before you notice a damage on the spark plug?

Another question to cap70 finally as I did understood the coil circuit I understood the Tesla switch solution you proposed. It's look like very good idea. How far did you reach there ? Using my very limit EE knowledge the only problem is the switcher which should "carry" the big charge using transistor won't happen (?) using relay might be not fast enough.
Did you see this site (its gather info from thread from this forum):
http://drspark.com/idea003.php

@Cap70:
Th marine plug will ware eventually.

I am going to make the DC -DC circuit also soon. Is it fast enough for charging?

@HV:
Just cutting off the ground electrode wont work very well, not as well as the plug thats made for it. The gap might be a little too big. I have done it, but it misfires too much.

Is it fast enough for charging?

Yes, circuit is operated at 40Khz frequency it charges 330uF capacitor fast enough as fast as we can push the switch,
but the transformer I am using is not designed for such high current it becomes very hot immediately with 330uF capacitor,
But it is working best with 10 to 30uF capacitor.
I made mistake in selection of mosfet, mosfet must have high frequency operation with MOSFET driver otherwise gate capacitance of MOSFET creates problem at high frequency heating of mosfet is observed...circuit is same as previously posted.
I have taken trials with TL494 it gives control on duty cycle and output voltage, use of TL494 circuit gives more advantages, but It is giving me trouble.
TL494 advantages
1. Charging of capacitor when needed.
2. Maintains constant voltage. regulated output.
3. Load regulation and line regulation is possible.
4. Once the capacitor charged to desired voltage it goes into very low current consumption level. (When engine is off)
5. Soft start.

At present I am using CD4047 for DC to DC converter