Engine speed sensors using Hall effect?
I'm trying to measure the speed of a motor using the help of a Hall effect sensor. I know that the sensor turns on and off as the magnetic field passes by creating a square wave proportional speed. I thought about creating a band-pass filter through which the ideal diet is approximately 133 Hz with a bipolar magnet, if the frequency was in the range it turns a light indicating it was within his reach. I need to build a circuit to do this, it cannot be done with a scope. I could probably order any low-cost chip if necessary, but I want to keep it as simple as possible. Ideas?
One possibility is to use a 555 timer clock at twice the desired frequency. Use this fixed frequency signal and a lock toggle (flip-flop T) in a logic gate (AND or XOR) to drive the LED. If the motor speed is close to the reference speed, the light goes out Occasionally, depending on your tolerances clock circuits. When it is within the tolerance, the LEDs appear to be lit. An analog bandpass filter will be difficult to implement with any kind of reasonable accuracy at these low frequencies. digital is the way forward here.