> I am trying to use a CA3140E op-amp as a comparator.
> The two inputs are chemical sensors. The difference voltage between them
> can range between 400mV, to 50mV (100% concentration to 0% concentration).
>
> I remember reading somewhere in a text book, that if V1-V2 is greater than
> (I think) 100uV the op-amp will go into saturation.
>
> Can anyone a) clarify this for me, or b)suggest a better way to measure
> the difference voltage.

An opamp used as a comparator typically would go into saturation, especially
since you probably want to add a little hysterisis.  A saturated opamp may
take a little longer to respond to different input signals, but that should
still be much faster than your chemical concentration can change.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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