ICL7611 op-amp (was: Motorola MC14081B)

Adrian Graham witchy at binarydinosaurs.co.uk
Sat Dec 24 06:09:11 CST 2016

On 24/12/2016 04:34, "Glen Slick" <glen.slick at gmail.com> wrote:

> 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

Ah cool, I was watching some of Dave's tutorials yesterday but in one of
them he lost me completely towards the end, talking about Virtual Ground on


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