I just took the receiving device (generator controller) apart and the terminals for the magnetic pickup (that I am trying to simulate) go to a transformer. The manufacturer's data for troubleshooting the generator controller says that the impedance of the input terminals should be around 220 Ohms. Indeed, when I put an Ohmmeter on the input terminals, the impedance is 223.4 Ohms. The magnetic pickup on the generator normally outputs up to 30 volts AC but less at lower generator speeds (startup, idle, etc.). I figure that with my power supplies, 20-25 VAC should be fine.
I have developed a 1 volt signal by programming a PIC to output a square wave and then running the square wave through some Op Amp integrators to make a sine wave, then through a AGC circuit to get a constant signal amplitude (since the integrator output signal level decreases with increasing frequency) and now to the final stage - amplifying the 1 volt signal from the AGC to the 20-25 Volt signal needed by the transformer on the generator controller.
What else would you like to know??