Need a Signal from a Diesel Injector

[Thedrive2112]

Hello all, I need to get a signal from a diesel injector. My understanding is diesel injectors work on voltages around 70vdc and around 1 amp. I was thinking of using an opto-isolator but I also was thinking a 12v zener would work and would make for a simpler circuit. Does anyone know if a zener adds resistance? I don't want to change the resistance of the injector.

The injector signal from the vehicles ECM is a square wave. Whats the best way to convert it into a triangle or sawtooth? I was thinking send the signal into a 555 ic

 

[Arouse1973]

My first thought would be to use an opto isolator whose output is configured as a common collector this will provide a good deal of isolation to the rest of the circuit. How pure dose the triangle/sawtooth waveform have to be?
Adam

 

[Thedrive2112]

Adam thanks for jumping in and helping out.
Doesn't need to be very pure. Im basically looking to use the injector signal for timing but I was going to feed the signal into a compairitor so I could control duty cycle so the square wave generated by the ECM for the injector won't work.

 

[Arouse1973]

Ok so it could be as simple as a passive integrator then. The problem comes if the frequency of the injector timing changes, will this happen? Do you know the frequency of the injector square wave?
Adam