Miata Mailing List: October 1999, Message #182

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>From what I've seen they usually use the same setup based around an LM3914
(National Semiconductor), which will convert an analog input voltage to 10
outputs (LEDs). I'm sure even that fancy Hal-meter uses these things (3 per
unit,multiplexed). I have a feeling the J&S dual sensor uses two, one for
knock display and one for A/F ratio.

So, yea, they pretty much are all the same... of course, I haven't seen ALL
of them.  They all read an analog voltage and display it on a linear scale
(the LM3915 is log based, but not a good idea for this application.

O2 sensors can have different response characteristics from one type to
another. On most, if not all, the relationship between A/F ratio and voltage
output are FAR from linear. It looks like something between a sinusoid and a
square wave, where the 'jump' is at 14.7 (I think that's the ideal stoic
ratio). The voltage usually ranges from 0-1.2v, but that's not set in stone.

-Ryan

----- Original Message -----
From: Greg Germar <ggermar@mydestiny.net>
To: SSCOR <sscor@avatar.com>; Miata.Net ; Miata Power
<miatapower@rampage.net>
Sent: Friday, October 01, 1999 6:32 AM
Subject: SSCOR A/F meters...all the same?


> Hi!  This may be a dumb question, but are all A/F meters the same?
Meaning,
> they aren't picky about what O2 sensor they are wired to?
> WRT O2 sensors, am I right in saying that no Miata ever came with a 4 wire
> O2 sensor?
>
> Thanks!
>
> Greg
> 96 BRG
>
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