triggering an HEI module

[Jack E. James]

Hi,
A gracious post from another, the input polarity is important to set dwell
periods, module

ftp://ftp.diy-efi.org/incoming/3334rev0f.pdf

triggers well from most sensors like older Ford and Chrysler, I've used it with
a resistive load to condition crank and cam sensors also.
JJ

Bruce Plecan wrote:

> IF that were true there would be  no timing change reguardless of how the
> reluctor is wired up.   What you mention is what GM teaches, which ain't the
> truth on that item.  Sorry to crush you with the horrors of the truth.
> <g>...
> Bruce
>
> > 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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