DIY-WB Output Voltage Scaling

[John Lamb]

Are you saying that the Display has an embeded PIC that allows you to
program a segmented curve fit?
That's what is needed here to linearize the output.
Another method is to use the an A/D to address memory locations that
linearize the output.
Sorry if this is old discussion.

JL

Peter Gargano wrote:
> 
> It should be pointed out that the current incantation of the
> DIY-WB unit has a non-linear voltage:AFR transfer function.
> The actual transfer function is described here:
> 
>   http://www.diy-efi.org/diy_efi/projects/diy_wb/
> 
> See "Output voltage/AFR reference". A graphed version is here:
> 
>   ftp://ftp.diy-efi.org/incoming/DIY_WBafrVolts.gif
> 
> The curve can be thought of as a series of straight lines
> for simple interpolation, but it means that a simple digital
> panel meter connected to the WB output with a simple scaling
> circuit will not be able to show accurately a large range of
> AFR ratios. This is why I suggested the Jaycar kit/Silicon Chip
> kit with 16F84 PIC and 3 digit display that comes with source
> code that could be modified to scale the DIY-WB's output to the
> above transfer function.
> 
> If you're logging the DIY-WB's output and post-processing the
> logged voltage, then this isn't too much of a problem.
> 
> For the DIY list, here's the information I posted to GMECM
> yesterday.
> 
> Product Name:        DIGITAL FUEL MIXTURE DISPLAY KIT
> Catalogue Number:    KC5300
> Price:               AU$62.95  (less than US$35) + freight
> 
>   http://www.jaycar.com.au/home.htm
> 
> Peter.
> 
> Disclaimer: I have no affiliation with Jaycar, and their
> web site is a bastard to use.
> 
> (Jaycar - fix it!)
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