Vasile Surducan ha scritto:

>> Thank you Vasile: linearity is not a problem, I can do it in software.
> 
> I heard this too many times. Software does not compensate a wrong
> defined problem.
> Repeatability is a matter of temperature variation. A zener will do it
> only if has zero thermal drift. If you still want this method, search
> for a zener around 5V-6.2V where most of zeners are changing
> characteristic (negative to positive)
> http://www.microsemi.com/micnotes/203.pdf
> and do an active zener using a transistor. Optocoupler thermal
> variation will still exist untill you'll compensate it.


I understand that, Vasile. That zener above should not dissipate much 
power, since it only has to power a PIC doing nothing but generating 
pulses one in a while.

I stressed the point that I could compensate "static" linearity in software.


>> Accuracy i.e. "repeatability" would be.
> 
> BTW accuracy and repeatability are two different things.


Yes I know :)

In some sense, accuracy per se is not such an issue in this case. But 
repeatability would be.


BTW: nobody has replied to the datasheet that I posted, from Fairchild, 
showing the "aging" of an optoisolator...
:)
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