This is Efficient flyback driver circuit, a good and fairly efficient flyback driver circuit. All parts can be obtained easily from Radio Shack, including the MOSFET. This circuit uses a 555 timer IC to pulse a 2N2222 with square wave at a frequency that is set by the capacitor and the potentiometers.
The 2N2222 then drives the gate of the MOSFET and the MOSFET delivers the pulse to the ten turn winding on the flyback. If you build this circuit you will have to adjust the potentiometers until you get the longest arc possible. The circuit will run from +12VDC to +15VDC at about 3A.
The MOSFET must be heatsinked! This is important if you are going to run this for any decent amount of time. If the MOSFET still gets too hot or burns up you can place a 4 ohm (for a +12V supply) or a 5 ohm (for a +15V supply) between the source lead of the MOSFET and the primary on the flyback.
Make sure that these resistors havethe proper power rating for the voltage and current that they will be carrying. The flyback should be wound with ten turns of 14-16 guage solid wire. Anchor it in with some electrical tape. Any previous primary windind should have already been removed before winding the new one.