555 for MAF

[William Shurvinton]

I don't like presenting schemes that I don't currently have time to build
and test, BUT. Every home has at least one old scrapper PC. These have a
very nice parallel port that gives 8 outputs, 4 inputs and an interrupt
line. If you hooked a fixed frequency oscillator at the max speed or
resolution that you need, a simplish piece of code would allow you to have
variable outputs, with niceties like the VSS would track the speed and you
could see the ECU commanding gear shifts etc.

Whether it could emulate the fine crank sensor would need investigation, but
thats only about 20KHz which should be well within capabilities.

If the whole idea got out of hand it would require some external logging
boxes with ADC and DAC capabilities, but if you just wanted CAM, Crank, VSS
and a couple of controls and inputs it would not be a huge task.

Bill

NB in a few weeks my '727s arrive, at which point I may start getting
interested again.
----- Original Message -----
From: Bruce <nacelp at bright.net>
To: <gmecm at diy-efi.org>; <diy_efi at diy-efi.org>
Sent: Sunday, February 16, 1997 3:05 PM
Subject: 555 for MAF


>
> The only program I have for finding values for generating a given freq
with
> a 555 always tries changing 2 values when I try to go for two different
> freq.
>
> I would like to generate a 30-130Hz output from a single 555, and single
> pot.  If it goes off scale in either direction some, no big deal.
>
> Any help appreciated.
> Bruce
>    Applied power to the ecm bench and no smoke exscaped (at least so far)
> <g>
>
>
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