triggering an HEI module

[bcroe at juno.com]

The signal into an HEI module is far from a sine wave. It
looks like a slowly rising voltage which rises faster and
faster as the pole pieces come together.  Just as the poles
pass peak, the voltage very, very  quickly reverses polarity
to about the same but opposite voltage.  Then it decreases 
like a mirror of the first part.  Then it crosses zero and starts 
climbing again for the next pole alignment

The spark is triggered by that very rapid voltage reversal at
the peak pole alignment.  The amplitude varies a lot with
speed, but the point of reversal is consistant.  Bruce Roe

On Thu, 8 Mar 2001 19:59:23 EST Tedscj at aol.com writes:
> Hi,
> Has anyone tried to determine what type of signals will trigger an 
> HEI module?
> To be more specific with what I want to achieve:
> I have a little foreign four banger with a really pitiful points 
> ignition.  I 
> was thinking of converting it to GM DIS as a first step towards 
> full-blown 
> GM-EFI.
> The problem is that the only after-market conversions from points 
> available 
> for this car are to 'optical sensor' ignition, which will result in 
> a square 
> wave signal from 0v to 12v.  I know HEI modules (and DIS) are 
> looking for a 
> sine wave.
> Does anyone know if a square wave will trigger the module?


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