Thomas Ryckmans wrote:
This circuit is not good. Most of the power will go to the resistor in series with the diode. A simple capacitor with a diode in parallel with the mosfet (that it probably already has) is much better. I have some flybackI would need some help to design a MOSFET circuit to run an ignition coiland was wondering if anyone n this list could give me advice. The circuit looks very much like this one below- just my signal generator is a bit more complex, and my MOSFET has higher ratings http://www.electronics-lab.com/projects/misc/001/index.html
circuits here (not online now due to heavy rain in the city): http://www.coe.ufrj.br/~acmq/flybackIgnition coils require more current and lower input voltage. A serious problem in using flyback circuits to drive continuous sparks is that the flyback circuit works in continuous mode, drawing a huge current if no control or current limitation is added. With a 555 driver, you can add a small value resistor between the drain of the mosfet and ground, and use the voltage over it to drive an NPN transistor through a resistor in series with its base, that has the emitter grounded and the collector connected to pin 5. This will reduce the duty cycle of the 555 when the mosfet current is too high. More sofisticated flyback drivers using a controller as the ones used in many switching power supplies already have this function. The drivers in my page above can drive a Jacob's ladder if a series resistor is used, but the result is
not very impressive. http://www.youtube.com/watch?v=E7rlhcM3s7c Antonio Carlos M. de Queiroz _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla