WBO2 display

elcamino73 elcamino73 at mindspring.com
Mon Oct 22 23:10:14 GMT 2001


If you get this working drop me a line. It's a wee bit much for me to make
from scratch. But it would be nice to have direct afr readings!
----- Original Message -----
From: "Robert W. Hughes" <rwhughe at ev1.net>
To: <diy_efi at diy-efi.org>
Sent: Monday, October 22, 2001 12:42 AM
Subject: WBO2 display


> > There is no off the self unit that will take the WB O2 output and
directly
> > convert it to an AFR for display, if that's what your looking for.
> I have been siiting on this hoping to put a WBO2 together and build a
> working display before talking about it but here is what I have planned
> (this is similar to an idea another lister presented earlier also).
>
> The output of the WBO2 is connected to a 12bit A/D (finally found one
> cheap enough). This 12 bit output is connected to the address lines of a
> pair of 2732s. Stored in the 2732s at each address is the equivalent AFR
> in BCD without the leading 1. This will require 8 bits of one 2732 and
> four bits of the other 2732 to generate 3 digits. The outputs of the
> proms are tied to three LED driver chips connected to 4 seven segment
> LED displays (The high order display is hard-wired to 1 so the display
> can show 10.00 to 19.99). As a possible enhancement, the 4 unused bits
> of the second 2732 could be loaded with the correct voltage out for a
> NB(narrow band?, like most cars use)O2 sensor and this connected to a 8
> bit D/A converter to simulate the NBO2.
>
> This approach is not particularly low in chip count or elegant in
> programmability but all the parts are cheap and anyone who can program
> the Eprom for their car can duplicate it.
> --
> Robert W. Hughes (Bob)
> BackYard Engineering
> 29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
> Houston, Texas "The city with too much Oxygen"
> rwhughe at ev1.net
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