signal from coil and back emf......

[Tony Bryant]

<snip>

> to 12 volts with a 555c. The coil back-emf from a 2 ohm injector is
> negligible - I would use the low impedence units with a limitting
> resistor to start with, then go to a peak and hold driver if necessary.
> 

The back emf of injectors is only limited by the zener in the driver 
- generally a 39V zener (see the LM1949 docs). This back-EMF is vital 
in allowing the injector to close fast.

More than enough to pop a cmos gate.