Time for saturation???

[thomas walter x5955]

> Wondering if I could find out the length of time it takes an ignition coil to
> energize (roughly).  Also, does one need to let the coil reach peak
> saturation or is, lets say, "half charged" enough to get a good spark.  Would
> appreciate the help.  Thanks

If you have a current probe for your o-scope it is fairly simple to observe
this. 

ONE example. The coil fitted to the four cylinder Datsun's will clamp at 8
AMP maximum (ramps up to that point, then the module holds at that current).
Lots of time to "ramp" the current at lower engine speeds (50 ms), and
higher RPM you may need less of a 'spark' to fire the mixture (3 ms between
events).  Should give you an idea of the "ramp time" needed. [4cyl engine
with one coil from 600 rpm to 9,000 rpm].

Tom Walter
Austin, TX