How to convert pulses of a spark coil of an automotive engine to simple square waves

[Faizan Jawaid]

Hi ppl...somebody could tell me how to convert pulses of a spark coil of an automotive engine to simple square waves so that i can read these square waves to measure frequency and the RPMs of my car?

 

[flatulent]

Re: RPM of Engine

One simple way is to limit the voltage to 3-5 V and feed it to a divide by two flip flop. Then you double the reading from the counter you use. This is easy to do by append a LSB of zero if you are using a binary counter.

One thing to look out for is the ringing of the spark voltage. You may need to use a RC network to smooth out the pulse and then use a schmidt trigger gate.