[sdiy] Summing op amp calculation fail

[Paul Perry]

More helpfully, http://www.intersil.com/data/an/AN9757.pdf
"A Cookbook Approach to Single Supply DC-Coupled Op Amp Design"

The problems arise because of the direct coupling.
Most examples on the web are for AC coupling.

----- Original Message ----- 
From: "Neil Johnson" 
> George is spot-on.  There's no mystery, just basic maths and an  
> understanding of what an op-amp does.

paul perry Melbourne Australia