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Date:         Fri, 28 Jul 1995 15:44:19 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Erik Soule"  <erik@henries.nsc.com>
Subject:      Re: O2 Sensor - lean/rich indicator

In message <9507282115.AA02041@superior> writes: > This is a question for the "electronically inclined" out there. How > difficult would it be to set up a three LED indicator that would tell the > driver if the O2 Sensor is reading rich, lean, or "stochiometric" for one > and three wire FI systems? Such > a device might be helpful as a way of assessing basic driving habits and > engine tune. > > Thanks for any ideas. > > DC

I'm by no means an expert on O2 sensors, but I just happened to have a reprint of an article titled "Lambda closed-loop control" on my desk that I've been perusing.

I quoteth: "The voltage supplied by the lambda sensor as a result of the oxygen content in the exhaust reaches 800...1000 mV with rich mixtures (lambda <1), but it is only about 100mV with lean mixtures (lambda >1). The transition from the lean to the rich range lies at 450...500 mV." Reaction time is <50 mSec.

Soooo, you should be able to do it easily with a regulator and something like an LM3914 to drive the LEDs. You might like more than 3 to get the resolution you need. This is a pretty simple circuit if you've ever breadboarded a circuit. If not.......

I think someone on the list has a commercial version of this. If you build it yourself, the materials would be less that $10.

Happy (exhaust) trails.

-Erik

NSC Analog Automotive Systems Tel. (408)721-3476 Fax (408)721-8292 M/S C2611


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