I'm trying to build a variable ignition controller for my motorcycle, but in the beginning appeared a problem with voltage filtering.The uC cannot measure the engine speed is jumping between 1200 to 4000rpm, but the engine speed simulator is running at 1200rpm.
The ignition coil comes from Opel Astra F(16NZ engine) fuel injection and is shielded, low impedance coil 0.4 ohm.
Because the low impedance of coil, i need to vary the dwell angle.
The signal pickup is a hall sensor TLE4905(power comes from the uC 5v stabilizer)and the power output schematic is below.
My concern is about peak voltage coming from ignition coil when the secondary coil collapse(spark).
The power for uC comes from a 5V stabilizer and a 3300uF capacitor, the test power supply is a laboratory supply so there isn't any noise that perturb the uC.Same supply is for the ignition coil, only have 12V.
I've try to connect a capacitor 100nF...220nF and 1N4007 diode between coil input and the ground but unfortunately without success.