[Diy_efi] 555 timers

[paul b]

----- Original Message -----
From: "James Seabolt" <turbofiat at hotpop.com>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, January 18, 2005 9:00 PM
Subject: [Diy_efi] 555 timers


>
>
>
> You guys got me thinking over the weekend and I think I'm going to give
> this 555 timer a shot.
> I've had some experience with this chip. I built a timer that would turn
an
> LED on and off and when I was looking through an old shoe box, found the
> circuit still hooked up to the breadboard. That was almost 15 years ago!
>
> It's been so long since my Tech School days so I'm hoping someone will
> refresh my memory. If I can put anything to use from my Digital Circuits
> class, I'm hoping this will be it. Since I was unable to use my computer
> degree. I ended up working at a chemical plant instead after school.
>
> What I want to do is take the tach signal from the - side of the coil
which
> will be the trigger, feed that into the 555 chip which will pulse the
> injector. And use a potentiometer to adjust the pulse rate.
>
> I want to start out using a Bosch cold start valve since it would be
easier
> to mount. Perhaps use the throttle position switch to trigger a second
> injector under wide open throttle and boost.
>
> I downloaded some pages on the 555 timer but can't figure out what size
> capacitors I need. And what range the potentiometer needs to be.

this all depends on what time constant u want
the formula is T = 1.1 x R x C
T is in seconds
R is in ohms and
C is in farads

> The timer chip I have is stamped NE555N. Is this the chip that will
> tolerate 5 to 18 volts? Or do I need a different chip?
yes
>
> Also I'm a bit confused on the reset (pin #4). One schematic shows it tied
> to pin #8 (Vcc). Another one shows something else.
>
the reset pin is active low
ie. if its high the chip will operate if its low he output will be off and
the discharge pin will be low

> If someone could draw me up a schematic with what components I need that
> would be really cool!
>
> I'm off for the next three days (I work 12 hour shifts) and would like to
> spend time on my Yugo since it's too cold to do anything else this time of
> year.
>
> Is it possible to build a working fuel injection system by simply
> controlling the injector using just a tach signal? I know it probably
> wouldn't be able to adapt any better to temperature and altitude changes
> than a carburetor but I'm thinking it just might work.
i dont see why you couldnt just do the good ol' trial-n-error

>
> I'm having my doubts whether I am going to successful at getting my Yugo
to
> accept blowing through a carburetor so I'm looking toward fuel injection.
>
>
> James Seabolt
> Tennessee, United States
> Homepage --->>> http://users.chartertn.net/jseabolt/
>
> 2003 Subaru Baja
> 1987 Yugo GV
> 1980 FIAT 2000 "TURBO" Spider
> 1968 Ford Fairlane 500 (Not a Ford Galaxie!!)
>
>
>
>
>
>
>
>
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Stay Cool
ICEMAN

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