[Diy_efi] 555 Timer controlled EFI

[Daniel R. Nicoson]

I've found that digging into a project is always the best way to learn about
a subject.  I think that's why it is so hard for a kid to sit in school and
learn from a book and lectures.  Some of us just aren't wired that way.
Twenty years ago I had 5 semesters of calculus but it wasn't until I later
had an engineering course that really used some Fourier transfer functions
that I understood how they could be used and really how to manipulate them
(I can't remember any of that stuff now!).

The 555 is actually a very nice IC.  I use it for everything, almost to my
detriment.  I've been slogging along on a variety of projects for the last
three years and most of the circuits have a 555 in them.  Every time I come
up on a control issue that isn't linear I wish I knew my microprocessor
stuff already.  That will be my next stage of learning once I get the next
few of my projects completed, learn microprocessors.

The old timers used to use calculus to set up their analog circuits.  They
would lay out the basic idea and actually write equations to represent the
curved functions they needed to manipulate and then build with vacuum tubes.
Then silicone came along and things like opamps replaced various tubes but
the same process worked.  Now when we hit curvilinear functions it is much
easier to go digital and chop that beautiful curve into
rectangles...Amazingly complex devices worked very well and very fast before
we all started thinking digital...but I digress.

Take care,

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 11:28 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] 555 Timer controlled EFI
>
>
> Good comments Daniel. I did see your other post regarding the
> size of MAFs. And it stands to reason.
> When I first looked into this idea, I was looking for a
> replacement for a typical 2 barrel carb on a typical 4 litre 6
> cyl. The more I learnt about GM controllers, the more I felt I
> was re-inventing the wheel. If I were to use GM sensors
> everywhere, why not just use the controller and harness, and
> learn how to program it.
> So it got shelved. It still has the advantage of being easily
> tuned, especially if a WB02 is used.
>
> As for the learning curve, I think I learnt more about EFI in
> starting to design one, rather than just using one from the junk
> yard, with the aid of these posts. Several listers have ideas
> about using the idea on single cyl or stationary engines, it may
> shine in that area.
>
> As I have stated earlier, this is just an idea I have not yet
> prototyped. What I can say though, the 555 can be a bit tricky
> when mounted on Vero board. You must run bypass caps on the
> supply rail. When it resets, or discharges the timing capacitor,
> it can cause a surge, making the pulse length inaccurate. I have
> heard of the 555 being a bit unstable. Could be the same cause.
>
> Geoff H.
>
> PS please don't ask me to define a typical 4l 6cyl eng. LOL. Try
> a 70s. Silly comment this day and age.
>
> ----- Original Message -----
> From: "Daniel R. Nicoson" <A6intruder at myo-p.com>
> To: <diy_efi at diy-efi.org>
> Sent: Saturday, January 21, 2006 2:50 PM
> Subject: RE: [Diy_efi] 555 Timer controlled EFI
>
>
> >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
> >
> >
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