o2 meter

[Tony Cooper]

Tom Cloud wrote:
> 
> >No what they mean I think is that it needs a VERY good earth. A direct
> >connection to the Neg terminal of your battery works - at least it works
> >well how I have done it. The sensor will ground out through the engine -
> >it has a very good connection to the battery ground, via the engine
> >earth strap.
> 
> no, the "earth" / "ground" connection is for the power source.  In
> any circuit you need a minimum of two wires for power and two more
> for signal.  Many times the signal return and the PS common are
> combined (single-ended input).  In this case, it's obvious that
> there must be a floating input whose porpoise is to eliminate
> false readings due to circulating "earth" currents.  Connecting
> his signal return to the battery would probably make this situation
> worse, not better.
> 
> Tom Cloud
> 
>      A truly wise man never plays leapfrog with a unicorn.


No, what I mean is that to get any sort of signal from the sensor, it
mmust be fed to a very high impedance input - especially as the sensor
does not produce very much current. If the 'earth' connection is not
very good then this will screw up the value from the lambda sensor. What
is needed is a very low impedance power connection - I have done this on
my current project, and it works well, where as when I was connected to
the sensor ground, all I recieved was a cruddy signal at best..

Tony
-- 
Sent By tony.cooper at virgin.net