WBO2 display

[Robert W. Hughes]

> 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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