Thank you so much eetech00Hi
I haven't actually measured the field around a spark plug wire, but its strong enough to be sensed by a wire wrap or inductive pickup, so it can easily be sensed by a hall sensor.
In addition, the circuitry used for spark sensing must include signal conditioning before input to the remaining circuitry (ADC or otherwise). The A1203 is a hall bipolar switch that already contains conditioning circuitry. It can provides a pulsed DC output (triggered by the sensed spark) at whatever output voltage level needed (up to 30vdc). Cost is about 1.80 USD for the SIP version.
You could send the output of the hall sensor directly to the input of the Arduino (with appropriate overvoltage protection), compute the measured RPM, then display on an LCD, LM3914 with LEDs, or other display device. I haven't used Arduino before, only PIC micro's. Maybe someone else in this forum can help.
eT
I really appreciate your contribution to this thread and hope you will be doing the same on this whole forum..
I am attaching a file which I took from some where else... I just want you to compare it with your provided circuit in post #22 and tell me what is the difference between these two besides the voltage regulator circuit.
What do you think If I replace the UGN3030T in this circuit with A1203..... will it work????????