rpm

Hi There! I tried to make a DIY circuit to convert the modern ECU 5v pulse of RPM for my VW GOLF-2 which upgraded to GOLF-4 engine to the original 12v analog tachometer with the most known circuit of a relay coil, resistor and couple of diodes but it failed after 2000 RPM, it drops to zero when...

Hi I am trying to measure a speed of a rotating shaft that has gears on it for the Hall effect sensor. There will be 3 speed sensors. What device can I use to measure this speed sensor? The sensor produces a pulse with each passing gear tooth which produces a square wave. I figured that if I...