555 EFI

[Bruce Plecan]

-----Original Message-----
From: thergen at svn.net <thergen at svn.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Saturday, January 16, 1999 3:08 AM
Subject: Re: 555 EFI

I just reread this and think maybe I got more.
Well, I'm gonna flood the list with dumb stuff today.
Anyway use like a 2M, and 1M resistor for the bias v to pin 5, and then
tie a 324 output to that to move it up?.
How would say a TPS 0-5 be feed to the 324?.
Cheers
Bruce

>Picture an op-amp with the non-iverting input connected to pin 6 and the
>inverting input connected to pin 5.  Pin 5 is also connected to a resistor
>divider network that pulls it to 2/3 Vcc.  There is probably a symbolic
>view on one of the semiconductor manufacturers sites.  I'm looking at the
>cover of two different books that show this configuration.
>
>The 2/3 reference point can be yanked around to where you want by using
>pin 5.  It can also affect the 1/3 reference for pin 2.
>
>The pin numbers above assume the 8 pin package.
>
>If you can't find an online reference, or it's still not clear, I could
>probably try some ascii art to show the configuration.
>
>Tom
>
>
>On Sat, 16 Jan 1999, Clarence L.Snyder wrote:
>
>> Bruce Plecan wrote:
>> >
>> > -----Original Message-----
>> > From: Clarence L.Snyder <clare.snyder.on.ca at ibm.net>
>> > To: diy_efi at efi332.eng.ohio-state.edu
<diy_efi at efi332.eng.ohio-state.edu>
>> > Date: Friday, January 15, 1999 11:57 PM
>> > Subject: Re: 555 EFI
>> >
>> > >thergen at svn.net wrote:
>> > >>
>> > >> Bruce,
>> > >>
>> > >> Are you thinking of a string of one-shots and using a varying
>> > >> voltage on
>> > >> the control pins to vary the output pulse width?  If you're already
going
>> > >> to be using op-amps to scale the output of the sensors, you could
>> > probably
>> > >> add/subtract the outputs of multiple op-amps together through
resistors
>> > >> and run that into the control voltage pin of a smaller number of
555s.
>> > >>
>> > >question of clarification:
>> > >what is the "control voltage" pin? My understanding of the 555
operation
>> > >is the cap and resistance (cap between threshold {connected to
discharge
>> > >for monostable}and ground - resistor from B+ to threshold) were an RC
>> > >"tank" circuit. The resistor controls the time required for the cap to
>> > >reach 2/3 of B+ voltage.
>> >
>> > Pin 5 sets B+ as you discribe it.
>> > Bruce
>> >
>> >
>> What do I connect to pin 5, through what, to control this? On the info I
>> have, this is the BYPASS pin and is tied to ground through a small cap
>> to despike. How do I use it to control pulse width? What degree of
>> adjustment is possible from this pin?
>>
>> Another question -
>> What percentage pulse width change would be required from the MAP or TPS
>> input? What percentage from  engine temperature, assuming these were the
>> only inputs you were going to use other than the trigger (tach sync)?
>>
>