flip flops to drive ignition

[Joseph Obernberger]

Chris Conlon wrote:

> At 04:28 PM 1/15/01 +0800, Dan Zorde wrote:
>
> >How about using the ignition outputs to drive a couple of Flip Flops, then
> >you could tie opposite cylinders to the Q and Q(not) outputs, thus every
> >time the ignition driver fires it toggles the FF to alternatively drive the
> >coils.  You'd just need to figure out some way to overcome this 1/10 sec
> >auto fire Orin was talking about.
>
> A friend of mine has a system that works along these lines.

That would be me!
:-)
It basically works along those lines - but you need to have some sort
of reset for the FF.  In my case there are two position sensors on the
distributor - when either of these sensors (OR) tripped, it would
reset the FF.  The normal ignition signal that would normally go
to the ignitor was used for the clock input.
<http://josepho.www4.50megs.com/ignition_project.html>

> The stock Toyota ignition driver runs off a logic level signal, +5
> to charge the coil, drop to 0v to fire. I *think* at one point he
> was using 3rd gen RX-7 coil packs, which are apparently waste fire
> but with the same type of drive signal. Supposedly they have a
> pretty hot spark too.

Yes - it was using RX-7 twin tower (leading edge) coils.  They seemed
to be happy with long duration pulses - stayed cool to the touch even.

>
> Another issue he ran into at one point was conditioning the reluctor
> signals. This caused some hassles. Also since the reluctors were still
> needed by the stock ECU, it was important that the circuit didn't
> interfere with that operation. 2 parts that may be helpful: the LM1815
> (Nat Semi), which is an IC designed to deal with reluctor signals, and
> MSD's p/n 8209 ignition stabilizer, which is probably not much more
> than an LM1815 in a box, with a digital output.

I need to check those out!  Since it got cold, the signal conditioning
portion of the circuit doesn't work very well to condition those
reluctor signals and I get an occassional miss.  Perhaps I should awaken the
project again.
Thanks Chris!
                                                joeo


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