DIY_WB on Electromotive

[Ron Schroeder]

At 03:17 PM 9/27/01 -0500, you wrote:
>My table is adjustable with 10 data points that I can calibrate a particular
>voltage to a particular AFR, so as long as the output is between 0v and
5v, it
>should work just fine.

>Don't really need to linearize it as the software will do that between
>datapoints, it would just be a matter of selecting the correct data points
for
>the table.

That is what I figured.

>I believe the usable output of the DIY_WB is about 1.40v to 2.90v - although
>being able to handle 0 thru 5v on the input side of the voltage converter
would
>probably be a good idea.
>
>Thanks
>Gabe


Hi Gabe,

So your input range is 1.5 volts centered around 1.65 volts and you want an
output of slightly less than 5 volts to 0 volts.

You need an op amp in the classical inverting configuration.  I would start
with a feedback resistor of 27K and an input resistor of 10K.  Instead of
connecting the + input to ground, connect it to the wiper of a 5K pot with
a 5K resistor.  Connect one end of the pot to ground and the other end to a
5 volt reference.

With 1.65 volts on the input, adjust the pot for 2.5 volts out.  The
usefull range of the DIY-WB will then become about 4.5 volts to .5 volts.

Ron Schroeder
WD8CDH
E. E. S.
wd8cdh at bnl.gov
rjs at bnl.gov
ron at 112motors.com
631 344-4561 Day
631 286-5677 Nite
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