How do these RPM sensing wires work? How do they "transmit" the RPM? Is it with lowering/highering the voltage on it? Sending a pulse or something? Thanks!
this one took me a while to work out but basically you get a square wave out of them but you need to plug them into a load i think (i just used an and gate) then you get 2 pulses per revolution hope this helps
well, to be exact, the rpm output wire doesn't give out a pulse signal. It just goes from being HZ (high impedant) to Ground 2x per rev. So it goes: HZ - Ground - HZ - Ground .. (you get the picture) That's why u'll never measure any voltage on that wire if you connect a voltmeter to it. And i think it uses a Hall-switch (which reacts to magnetic fields, usally south-poles) to do this switching. So in short, if you want to be able to measure this signal with a frequency meter or something, you have to use a pull-up resistor with the rpm wire.
