[Diy_efi] 555 Timer controlled EFI

[Daniel R. Nicoson]

I haven't been following your discussion throughout but I'd like to offer a
couple comments.

First I think it's an interesting idea to base a EFI around a 555 but I
don't think it is very practical.  With the price of the lowliest 8-bit
micro processors less than $5, you're going to make yourself crazy making it
work compared to going with a simple digital system.  To much stuff is not
linear...

Enough negative.  Here's a couple positives.

1) If you are going to run an engine with a 555 chip, the "restriction" of a
MAF is the least of your problems.

2) If you size a MAF for the engine at hand, it is not a restriction.  By
sizing it, you have ensured it will flow more air than your engine can
possibly use.

3) If you want a MAF with an analog output, use a Ford MAF.  The use 12 volt
power, a 5 volt reference voltage, and they output a 0 - 5 volt signal.  No
it is not a linear transfer function.

4)  Has anyone started bread-boarding this controller?  It is interesting
what you learn as you are bread-boarding circuits like this.

Good luck,

Dan Nicoson


> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
> Behalf Of Geoff Harrison
> Sent: Friday, January 20, 2006 8:21 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] 555 Timer controlled EFI
>
>
> Scotty, you are correct with the freq to voltage conversion. I
> saw TTL somewhere.
> With the GM MAP sensor, you get a variable resistance which is
> easy to convert to variable voltage, and feed that to the
> modulation pin on the 555.
> Also, I don't like any restriction the manifold, (except a
> throttle plate). So, if I had to use a MAF, I would go to the
> hot wire type, but those too have their problems.
>
> Having said that, one beauty of this approach, is it can be easy
> to set it up to suit your requirements.
>
> Cheers,
> Geoff H
> ----- Original Message -----
> From: <ScottyGrover at aol.com>
> To: <diy_efi at diy-efi.org>
> Sent: Saturday, January 21, 2006 11:33 AM
> Subject: Re: [Diy_efi] 555 Timer controlled EFI
>
>
> >
> > In a message dated 1/20/06 4:20:50 P.M. Pacific Standard Time,
> > geoff_h at smartchat.net.au writes:
> >
> > Having a  linear output is great, but my concept was to avoid
> > the
> > added complexities  i.e. in this case a D/A converter. The
> > main
> > concept was to have a system  that was easily adaptable to
> > almost
> > any engine, and tune it on the road by  a co-driver. I know
> > this
> > can be done with newer systems, with the  aid of a hand piece
> > or
> > laptop but then the co-driver has to know how to go  about it.
> >
> > Geoff Harrison
> >
> >
> >
> > You wouldn't need a D/A converter; a Frequency-to-voltage
> > converter should
> > do the job.
> > Scotty
> >
>
>
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