I need to drive my mechanical speedometer from a hall effect impulse

Thread Starter


Joined Apr 16, 2016
I have recently changed my gearbox, and the new box has no speedometer output
so I have made a 36 segment disc to put on the propshaft so now I need a board 12v driven with adjustment
to couple to a motor to drive the speedo head. Can any one recomend a proprietry board or a circuit diagram
that I can use as I wish to retain the original Speedometer


Joined Jul 18, 2013
Did you calibrate the speedo to find the rpm required/mile indication etc?
You could maybe utilize the pulses direct or multiply and feed them to a stepper motor drive step pulse input terminal.
But obviously some calibration is going to be needed.
A SIMILAR thread was started recently. Add-on cruise control used the driveshaft sensor.

The easist is likely a ucontroller that:
1) measures the frequency or period and converts to speedo RPM.
2) A motor with some sort of tach signal (encoder, analog) that can be controlled at a specific RPM.
3) The motor would be pulse width modulated to control speed.