I am try to read in RPM via a hall effect sensor and output the RPM as a signal that is similar to a coil and magnet tachometer. I have spent hours researching the web and all forums I can find.
Project: have an old tachometer that will only read in a signal like a coil pickup with a spinning magnet. I have motor that will exced the the max RPMs of the tach.
I need to read in the actual motor RPM via a hall effect or some other sensor, and output a signal the tach can read and cap it at 2000 RPMs the max of the Tach. The tach will read actual RPMs until it hits 2000 and will never go over that. I have been able to read in the RPMs and cap the RPM in a serial monitor, just need to figure out the signal to the tach now.
Please help, or let me know if it is possible or not.
I'm not sure of the actual tachometer requirements. It may react on the power or frequency of the signal. If you can open it and find an analogue meter in it (moving iron instrument?), you can connect to that meter and remove eventual other components (resistors...). Then you can feed the meter by a PWM signal, of sufficient (find out) amplitude, of any frequency. When the meter jitters too much, increase the PWM frequency. An amplifier (transistor/FET) may be required to drive a meter of low sensitivity, and a back-EMF protection diode.
You can try the same without opening the tach as well, but then you may need more power for the signal. Apply some DC current until the meter reacts, then reverse the polarity and try again. When the meter reacts in the same way, it's most probably the mentioned moving iron instrument, capable of measuring AC as well as DC. Then find out the required voltage and current for the peak indication (2000), and build an corresponding amplifier and power source for use with an Arduino PWM pin.
