Wide Range O2 sensors

[Roger Heflin]

> 
> 
> Hello,
> 
> I'm sure this topic has been discussed many times over, but I've been off
> the list for 6 months or so and am just now returning.  
> 
> Due mainly to the fact that Honda and a few others (we use them on Natural
> Gas engines at Deere) are making sales volumes increase, the wide range (5
> or 6 wire) o2 sensor sold by NGK/NTK is coming down in price.
> 
> Does anyone know of any affordable devices (even an oscilloscope) that can
> display or convert the output of this sensor into some meaningful value,
> other than the spendy converter box sold by NGK exclusively for the sensor?
> 
> Absolute precision isn't required-  I'd just like something wide range that
> is at least repeatable.  I know that these sensors are individually cal'ed
> - either at the sensor with a pig-tail resistor or something, or as a
> trimming value at the meter that is reading the output.  
> 
> >From experience, if the cal is wrong for a particular sensor, you aren't
> that far off... (Alleviating the need to cal if you can live with some
> error if you are more concerned with repeatability)
> 
> Thanks,
> Brock 
> 
If you can get a pc near it with a sound card you could make it work
that way.  Also with a bit of work and a small circuit you can read
data in and out of the printer port at rates that should be great
enough.   With both of these you are going to have to take the data
curves and index the voltages in to them ato determine what the real
o2 content is.  With the sound card you would probably have to limit
the current and scale the voltage down to the correct range to work.
I think somewhere on internet there is a circuit and some software
to make a cheap mans oscope using a sound card.

				Roger