Continued from the EV Calculations Thread
KiwiEV, the 1.5 volts that you're supplying to the tach isn't really what the gauge needs. It is just a coincidence that 1.5 volts moved the tach to 4,000 rpm. A conventional 4 stroke piston engine will send a signal (a 12 volt signal IIRC) to the tach one time for every 2 rotations of the crank. I have heard of people placing inductive pick-ups on the front shaft of a Warp8 or similar double shaft motor, but that would send a signal to the tach twice as often as needed. I guess it depends on the car as to whether or not the tach would like that signal. How is it possible to divide the number of pulses by two?