3-30V (Sinking/Sourcing) to Arduino Input

Thread Starter


Joined Feb 19, 2010
The automatic selection feature was definitely on my wish list! I'd like to keep it in place.
I could however, increase the min. input value from 3 to 5v.

I did the calculations and I think im ok at 3v...
1.4v loss in the bridge
1.2v loss in the opto
that leaves me with 0.4 v at the constant current diode
If i look at the data sheet of the NSI50010YT1G, at 0.4v I should get ~3ma output.
The opto datasheet states that at 2.5ma I get 80% transfer. 2.5msX0.8=2ma
I only need a base current of 600uA and I have 2ma available in this configuration

Looks like it all works out...am I missing something?