Wow, seems like some people are having problems and some aren't.

What makes it hard for me is that I haven't seen this problem in my testing. I've never burned out a transistor, nor seen any random sparks except for one at power up (sometimes) and one at power down (occasionally).

I'm not sure how the software could make this spark continuously. A falling or rising edge generates an interrupt, the interrupt service routine then reads the pin to make sure the signal is actually high or low (whatever it should be), and only then loads a spark delay into the compare module of the timer. Only when the compare interrupt is generated should it fire a spark.

To see if the engine is running the software only checks to see if the timer has overflowed a certain number of times since the last pulse.


Some people are having Q2 (2N4401) burn out? Am I understanding the circuit right? Q2 should always be high, except to trigger the spark right?


For the continuous sparking... Has anyone checked that there is not excessive ripple in the hall signal? Maybe the magnet is only halfway triggering the hall and that is causing it to oscillate between high and low?


I will definitely be working on this to solve the issues. If I had encountered these problems I would have let everybody know. If anyone can explain exactly how and when the problems are happening that would help me replicate and solve them. I'll check to see if I can get the continuous spark problem and poke around to see what might cause things to be left in the wrong state.


-Jake