<<I am planning to build an O2 sensor for my car while I am at it...>>
Cyrille,
I think you have read my mind :)
I actually started designing a circuit to do exactly this a few months ago.
I was planning an O2 Sensor, coil LT feed and temp sensor.
>From these I was going to calculate rpm, dwell and o2. I even considered
fitting a proximity switch to use as a TDC sensor so then ignition advance
could be calculated.
I have attached a pdf which shows the circuit I designed for this (If
anybody else on the list wants it please ask and I will send it on)
In a modern car the ECU adjusts the mixture control so the oxygen sensor
output oscillates between about 0.1 and 0.9 volts, They really operate more
switch like than analogue. The ECU looks at the rate of oscillation of the
sensor to determine correct mixture. If the mixture is weak the ECU richens
it until the sensor swings over the reduces it till it swings back. It keeps
this up, so the faster the swings the more accurate the control is.
A quick Google turns up plenty sites that explain all this better than me.
Hope it helps a bit
Thanks
Duncan
[demime 1.01d removed an attachment of type application/pdf which had a name of
Visio-Eng Data.pdf]
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