ICL7611 op-amp (was: Motorola MC14081B)

[Glen Slick]

On Fri, Dec 23, 2016 at 7:48 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
>
> The op amp is configured as a schmitt trigger or comparator with hysteresis:
>         There is no negative feedback so it is operating at full gain and functions like a comparator.
>         However there is positive feedback via R412 (*1), this adds hysteresis to the trip point(s).
>         (Brief hackneyed, not rigorous, theory of op: As the input differential varies past the trip point, the output pulls the + input
>         further above or below the point at which it just tripped, so the inputs now have to 'overcome' a greater differential
>         to trip as the input differential varies in the opposite direction.)
>

A recent EEVblog video has some whiteboard explanation of using
positive feedback for hysteresis if anyone is curious...

EEVblog #941 - Schmitt Trigger Tutorial
https://youtu.be/Ht48vv0rQYk?t=13m43s