Ign Advance on MR-2

[David Hunt]

How about giving more info on the part number...etc of that Mag rel circuit?

dh


----- Original Message -----
From: "Les Newell" <les at lnewell.screaming.net>
To: <diy_efi at diy-efi.org>
Sent: Monday, August 20, 2001 4:23 AM
Subject: Re: Ign Advance on MR-2


> > I've heard a lot of talk about magnetic reluctor sensors and the
> associated
> > circuitry.  What about a Infra-Red emitter/receiver pair who's output
goes
> > through a Schmitt trigger?  This seems easier to design around...  What
am
> I
> > missing?
> The circuitry that is needed for magnetic reluctance sensors is actually
> quite simple. My circuit uses 2 diodes, two resistors and a comparator.
> Reluctance sensors are simple, reliable and dirt resistant.
> Infra red sensors have to be shaded from light and protected from dirt.
>
> >
> > I could have two wheels attached to the crank pulley, one with 1 tooth,
> and
> > one with 4 teeth.  I might have to run the output through a flip-flop to
> > reduce the frequency 1/2...  Then use a 2-bit counter to select one of 4
> > transisters to turn on, which in turn charge/discharge the coil.
> >
> > This seems simple, actually.  Am I missing something?
> >
>
> Why use 4 coils? Most DIS systems use two coils, one coil drives cylinders
1
> and 4, the other drives 2 and 3. This is known as a wasted spark system
> because each cylinder recieves two sparks per complete firing cycle, one
at
> the correct firing point and one just before the top of the exhaust
stroke.
> Ford Zetec engines are fitted with a neat double coil assemby with 4 HT
> leads which is ideal for a home-brew DIS. The only production DIS I know
of
> with 4 coils was a coil-on-plug system by (if I recall correctly)Volvo.
>
> How are you going to work out the advance?
>
> Les
>
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