Paul,

   Do you have a schematic for the Op AMp circuit? What kind of gain are
   you looking for?

   Joe Berki
   Limo EZ

   Yes we do. Bob White did it. We need a gain of two.

   The 555 pulse varies from 1 msec to 9.5 msec
   while the mass airflow sensor puts out 0 to 5 volts.

   We will make the gain adjustable for tuning purposes.
   Maybe one pot is all we need for leaning. The same pot that
   changes the gain. The 20K feed back resistor would become the leaning
   pot.
   --
   Paul Lamar ...No rotor no motor.


   Bob, I was looking through my op-amp drawer and I found two dozen
   TLC274's Are these about equivalent to the TLC272 ?

   --
   Paul Lamar ...No rotor no motor.

   Hi Paul,

   Yes, those are the 4 per package version in a larger package. They'll
   work just fine.

   On the question of richening the mixture, it is also possible to get
   nonlinear gain from the op amp by playing around with the feedback loop
   if that's found to be necessary down the line.

   Bob W.


   Thanks Bob.

   What would a non inverting version look like?

   --
   Paul Lamar ...No rotor no motor.




   You basicly switch your input and feedback circuits, and the
   ground/reference circuit pins. One input is labled (+), and one (-) the
   (+) is the non inverting input, and (-) inverting input.

   Craig Smith

   What is the theory on the use of the Zener diode?
   --
   Paul Lamar ...No rotor no motor.

Not having the specific schematic in front of me, I'm guessing it is
used as a specific voltage reference? clamping offset current? In
instrument applications, there is usually a pot associated with the
referenced pin for tuning zero, or a zener diode would have the effect
of an offset voltage level.
try http://en.wikipedia.org/wiki/Operational_amplifier_applications
For some better explanations and references.
Craig Smith


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