schmitt trigger using opamp

Schmitt trigger is mostly used to convert a very slowly varying input voltage into an output having abruptly varying waveform occurring precisely at certain predetermined value of input voltage. Schmitt trigger may be used for all applications for which a general comparator is used. Any type of input voltage can be converted into its corresponding square signal wave. The only condition is that the input signal must have large enough excursion to carry the input voltage beyond the limits of the hysteresis range. The amplitude of the square wave is independent of the peak-to-peak value of the input waveform.