VSS importance

[mrvette]

I hope your flip-flops work guys,  but I was told by someone in the know, that
the computer as part of it's failure analysis capabilitites will recognize only
a sine wave input......hope he's wrong,  but I don't think so....I ran my 7730
computer in my vette 350, direct port inj.  and only had the idle variation
problem, from lack of VSS signal....that is why I bought the right sender when I
knew that was the last difficulty....GENE

Bruce Plecan wrote:
> 
> -----Original Message-----
> From: T Hergen <thergen at svn.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Monday, September 28, 1998 6:23 PM
> Subject: Re: VSS importance
> 
> >If the ecm doesn't care about the duty cycle, you may be able to use
> >something simple (view with fixed width font):
> >
> >    Output will generate a pulse for each edge on the input.
> >    This doubles the average frequency.  The duty cycle will
> >    not be 50-50.
> >
> >I haven't taken the time to calculate the resistor and cap values,
> >but can if you're interested.
> 
> If you would, I'd appreciate it.  I'll breadboard it, and after verifing
> it, I'll have it posted at 332 incoming so anyone needing a 4000ppm
> signal off of a 2000ppm can do it.
> 
> By the same token, if someone would do a flip flop for going 4000ppm to
> 2000ppm, then we'd have this knocked, for lots
> of applications.
> Cheers
> Bruce
> >
> >
> >Tom
> >
> >
> >
> >On Mon, 28 Sep 1998 jdzura at csc.com wrote:
> >
> >> The problem with doing a one-shot solution is the analog nature of the
> frequency
> >> multiplication. Over time and temperature there will most likely be
> problems. The
> >> classic way to do this is to implement a phase locked loop with a divide
> by 2
> >> (D-FF) in the feedback path to the phase comparator. The output of the
> PLL before
> >> the flip flop will be exactly 2x the input frequency. I  can't remember
> the
> >> series, but there used to be a 4000 series Cmos PLL that had great
> application
> >> notes.
> >>
> >> The other purely "digital" way requires an oscillator to run a series of
> Flip
> >> flops that can be used to do the 2x frequency multiplication. This is
> essentially
> >> a zero order PLL. In either digital case, the circuit will take a few
> chips and
> >> some additional power. I believe I have read where someone sells an
> adapter for
> >> $50-60 already done. If it has been done and is only $50, you should
> probably buy
> >> it. Designing one will probably cost at least half that by the time you
> consider
> >> packaging, connectors, and a wirewrap board. Just my humble opinion and I
> have
> >> been an electronic designer for more than 15 years. If you still insist,
> let me
> >> know, and I will look up the reference to the cmos PLL chip. CMOS has the
> >> advantage of being run from 12 VDC and won't incur the overhead of
> voltage
> >> regulation.
> >>
> >> Joe D
> >>
> >>
> >>
> >>
> >>
> >> "Bruce Plecan" <nacelp at bright.net> on 09/28/98 01:48:00 PM
> >>
> >> Please respond to diy_efi at efi332.eng.ohio-state.edu
> >>
> >> To:   diy_efi at efi332.eng.ohio-state.edu
> >> cc:    (bcc: Joe Dzura/SED/CSC)
> >> Subject:  Re: VSS importance
> >>
> >>
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Mike Hoenes <MHoenes at dhr.state.nc.us>
> >> To: Jake Sternberg <chickens at ccwf.cc.utexas.edu>;
> >> diy_efi at esl.eng.ohio-state.edu <diy_efi at esl.eng.ohio-state.edu>
> >> Date: Monday, September 28, 1998 1:00 PM
> >> Subject: RE: VSS importance
> >>
> >> >anyone figure out how to get a 730  with a 91 L98 eprom to accept input
> >> from
> >> >a 2000ppm vss?
> >>
> >> Been figuring but not done yet.
> >> I'm assuming you want a 4000ppm, and only have a 2000ppm.
> >> What I think will work is use two 555 as monostables.  Trigger
> >> one off the - edge of the input signal, and one off of the + edge,
> >> then combine the two signals with a 4011 or some such, tie
> >> that to a Mosfet, and a resistor off of that and use the resistor's
> >> input as the VSS signal.
> >> ______            ______            ______            ______
> >>              I_____I             I_____I             I_____I
> >> ______   ___    ____    _____    ____   ____    ____
> >>              I_I      I_I          I_I           I_I         I_I
> I_I
> >> Hard to type with Doc laughing at my wave patterns
> >> Maybe some EE has input?.
> >> Cheers
> >> Bruce
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >

-- 


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