Hello.
I have a little issue regarding reading an rpm signal.
The rpm sensor is a 2-wire inductive pickup coil that generates a AC sine wave.
The sinewave frequency and amplitude vary´s between 600-1500Hz, and 5.5V to 12V. (measured between the two leads.)
Readings:
1560rpm | 5.5V | 610Hz
2280rpm | 7.8V | 860Hz
3800rpm | 12 V | 1480Hz
I´ve tried to read the signal by feeding in one of the leads into an optocoupler and grounded the other lead
I tried it and i got some readings but not until the rpm was quite high, so a measured the sine wave again
and realized that the amplitude had dropped significant.
So i lowered the value on the resistor (R23) , and it got better, but not good.
So I´m wondering, how should read this signal the correct way.
Maybe i should but it trough i diode and rectify it, then use a clamp diode to clamp it to something like 5 volt?
I hope you guys have some good tips.