Input pulses, output current

In series of my experiments, here goes again:

I am trying to interface a series of pulses that come from car's ignition systems, and because my tachometer electrics are broken (all that is intact is the coil that runs the needle and accepts current) I would like arduino to convert the pulses to current.

Can this be done?

probably, but you will have to do calibration.....

perhaps use interrupts on the arduino.... pwm a ssr or transistor connected to the 12V....

just shooting from the hip here..... :P

You don't need an arduino for this all you need is a monostable. Just use the pulses to trigger a fixed width pulse, then smooth that pulse with an R & C, then apply that voltage to your current indicating device. You might need an amplifier of some sort but you would need that with the arduino. You can make a monostable from an NE555 chip or a 74LS121 or 74LS123.