Home › Forum › Ask A Member › How do Atom Computer Ignition modules work? › Re: How do Atom Computer Ignition modules work?
The reason ive used a BC337 is that’s what is in the original Atom module. Its an NPN transistor Vce (collector-emitter voltage) is 50V, Ic (DC current) is 800Ma. Also the pin out conections are diferent on some other types of transistors. I have kept to the original component values as used in the Red Atom module. The only part I had to find was a suitable switching transistor that would work in the circuit. Even that in some magnetos needed an extra protection device, particularly with Wico magnetos in Seagull outboards. BC337 transistors are cheep here in Australia on Ebay localy for $7.00 for 50 freight free. Ken W don’t quite know how you got away with using the BD649 for so long. What was you using the module on? The killer on these systems is the HV spike as the transistor fires the coil, and its diferent on just about every brand of coil. The old Villiers coil was not as harsh as the Wico coil on the modules. When testing with the Wico magneto eventualy it would stop sparking, if left for a while it would be ok again. By fitting the Transorb diode across the switchlng transistor it cured the problem.