WB update: 1V output

[The Punisher]

You seem to know what you are talking about, would you consider posting a 
schematic of the circuit you described ? Just a simple jpg or bmp would 
plenty.


>On Wed, 14 Mar 2001 16:36:28 -0500 rr <RRauscher at nni.com> writes:
> >
> > Well, not really. The diy-egor has been placed on the diy-efi site.
> > However, the usage agreement stipulates the posting of new and/or
> > enhanced material to the gmecm list.
>
>Someone asked about getting a 0V to 1V output (like a normal
>OX sensor) from the EGOR output; Barry also mentioned that
>the signal ran in the reverse direction from normal.  This can
>be fixed with another amplifier, but changing a couple of
>resistors in the 11-6-2000 circuit will accomplish the same
>thing
>
>U3A (LM324) is a differential amp which responds to voltage
>across VR3 (284 ohms).  Since the RATIO of R9 (22K) to R12
>(100K) at the negative input is the same as the RATIO of
>R10 (22K) to R11 (100K) at the positive input, any voltage
>common to both sides of VR3 will be cancelled at the output
>
>First I would correct the direction of the signal.  Just reverse
>the connections of R9 and R10 to VR3
>
>Next adjust to 1 volt output swing.  The Web chart 7-30-00
>says the swing is from -2.214V to +0.52V, a total of 2.734V.
>We want to reduce that to 1V, which can be done by increasing
>R9 and R10 by 2.734V/1V, to 60.15K
>
>At this point I need to point out that the gain of the amp was
>100K/22K, or 4.545:1.  If the output swing was 2.743V, the
>input swing at VR3 would be 0.601V.  This voltage will
>only give 2.118 ma current change in a 284 ohm resistor,
>but the chart  says the current varies from -3.22 ma to
>+0.75 ma, or 3.97 ma change.  To get 3.97 ma for 0.601V,
>I am going to assume VR3 is really 151.6 ohms for the rest
>of these calculations
>
>Finally the swing needs to be adjusted to 0 to 1V relative to
>the ECU actual ground.  This can be done by changing the
>connection of the bottom of R11 from the virtual ground (4
>volts) to a different value.  The virtual ground doesn't figure
>in this value, since it gets canceled out.  A bit of ohms law
>shows R11 needs to connect to 0.811V above actual gnd
>
>Instead of looking for a 0.811V battery or another pot, I'd
>suggest using 2 resistors that have the Thevenin equivalent
>of 100k ohms in parallel (like R11) and 0.811V output as
>an unloaded voltage divider.  So R11 is replaced with a
>111.3K resistor from U3A  + to actual ground, and a
>986.4K resistor from U3A + to 8 volts.  Yes, I know you'll
>have to stick together several standard resistors to get
>such values; you decide how accurate you want to be
>
>So there is your 0 to 1V out.  Now I have questions.  First
>how does the free-air calibration work; just what gets
>adjusted?  How were the A/F ratios established for the
>7-30-00 measurements of 10.62:1 to 17:1?  Should we
>extrapolate to the sensors' 22:1 range capability at higher
>Ip + currents (if so the above need rework)?  Bruce Roe
>
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