Futterama
Member
Hello forum,
I have a simple gasoline engine (like Zenoah 26ccm for RC cars) with a ignition coil that has a special output - when the output is shorted, the engine stops (shorts the ignition somehow).
The output is some kind of AC, I'm not sure it's a perfect sine, but sorta. The voltage varies with speed, but it's about 40VAC at idle and rises to more than 100VAC when I open the throttle.
I would like to measure the frequency of this AC with a PIC, since it equals the engine rotational speed.
I don't want to load this output much, because I don't know if this would affect the ignition, so I would like some high-impedance circuit.
I saw Nigel mentioning zero-crossing circuits in another thread, is this the way to go?
I'm not much familiar with AC circuits, so consider me as a rookie
Any suggestions are very welcome.
Regards,
Futterama
I have a simple gasoline engine (like Zenoah 26ccm for RC cars) with a ignition coil that has a special output - when the output is shorted, the engine stops (shorts the ignition somehow).
The output is some kind of AC, I'm not sure it's a perfect sine, but sorta. The voltage varies with speed, but it's about 40VAC at idle and rises to more than 100VAC when I open the throttle.
I would like to measure the frequency of this AC with a PIC, since it equals the engine rotational speed.
I don't want to load this output much, because I don't know if this would affect the ignition, so I would like some high-impedance circuit.
I saw Nigel mentioning zero-crossing circuits in another thread, is this the way to go?
I'm not much familiar with AC circuits, so consider me as a rookie
Any suggestions are very welcome.
Regards,
Futterama