Editing Comparator (section)

===Zero-crossing detectors===
For this type of detector, a comparator detects each time an [[Alternating Current|AC]] pulse changes polarity. The output of the comparator changes state each time the pulse changes its polarity, that is the output is HI (high) for a positive pulse and LO (low) for a negative pulse squares the input signal.<ref>{{cite book |title=Electronics and Instrumentation for Scientists |last1=Malmstadt |first1=Howard V. |last2=Enke |first2=Christie G. |last3=Crouch |first3=Stanley R. |publisher=The Benjamin/Cummings Publishing Co |year=1981 |page=[https://archive.org/details/electronicsinstr0000malm/page/230 230] |isbn=978-0-8053-6917-5 |url-access=registration |url=https://archive.org/details/electronicsinstr0000malm}}</ref>