Electronic – Is this op amp circuit using both negative and positive feedback

operational-amplifier

In this question/answer theres this op-amp circuit:

enter image description here

I can't work out whats happening. At a glance the op-amp circuit looks like a cross between a schmitt trigger, differential amplifier and possibly an oscillator! Help!

What is it? What could ut be used for? How does it work? Please assume working knowledge of op-amps but not harder math such as calculus, transfer functions etc

Best Answer

It's a diff amp comparing the fixed value off the offset / null and the value of the sensor. The two 2k resistors look like atlantic attempt at hysteresis but don't seem like very good values.