This is a simple Schmitt Trigger Circuit Diagram. Schmitt trigger is a comparator circuit with hysteresis, implemented by applying positive feedback to the non inverting input of a comparator or differential amplifier. It is an active circuit which converts an analog input signal to a digital output signal. In this circuit A 555 IC is shown configured to function as a Schmitt trigger. Inputs above and below the threshold level will turn the circuit on and off producing a square wave output.
Schmitt Trigger Circuit Diagram