Op amping the O2 sensor

[Tom Cloud]

> Tom Cloud wrote:
>
>>the output is analog (i.e. it's not a quantum leap kinda thingie  ;-)
>>but it's function is far from linear, with it changing joltage
>>rapidly around stoich.  Output near zero for lean mixtures and
>>near 1 jolt for rich, with steep slope from about .2 volts to
>>.8 volts at stoich -- forget A:F range, but it's very narrow.
>
>  I saw one that had the steep slope you're talking about, and the range
>was I believe a few hundredths of an AF ratio, with the curve flattening
>out more slowly(and appearing to be marginally more useful) on the rich
>side, while the lean side did appear to be ALMOST like a switch, or step
>function. There was some useful info on this in a book called Understanding
>Automotive Electronics, although I would imagine the SAE papers would be an
>even better source. Do you know the numbers for these papers Tom? I'd like
>to read more on the temp. characteristics of the sensors, the book I read
>only covered it a little.
>
>Brad
>


There is a pretty good explanation of the EGO and a curve for it in Probst's
book -- though no real technical data.  I don't have any nos. on SAE papers.
Do a YAHOO search for "oxygen sensor".  There's several real good treatments
of them out there.

Rick Kirchhof has some data at
        http://mr2.com/TEXT/O2_Sensor.html

Lucas has a real good site at
        http://fiss.com/FILUCOS1.htm

very nice page by Bosch
        http://www.aaol.com/Main/AftMktMfr/Bosch/o2sensor.html

troubleshooting info
        http://www.forparts.com/o-21.htm
        http://filko.com/oxygen.htm

ad from Niehoff
        http://bwdautomotive.com/niehoff/things/o2flyer.html



My attempt at the curve:

1.0 V                                             *
 
 .8 V                                           *
 
 .7                                          *

 .6                                        *
                                          *
 .5                              ********
                                *
 .4                           *

 .3                         *

 .2                       *

 .1                      *
                       17    16    15      14     12
                      LEAN       STOICH          RICH

My graph is by no means to be considered correct (except for
the broad flat region at stoich and ~ .5 volts).  I don't remember
the A:F numbers -- above is a guess, maybe someone will fill in the
correct values.


Tom Cloud

 Clothes make the man ....  Naked people have little or no influence on society.