(Noninverting) An operational amplifier being used as a comparator to create a square wave. The op-amp compares the two inputs and drives the greater one into saturation, negative or positive. When fed a normal sine wave a simple square wave would be an output since it is being compared to 0 volts. But now that there is a DC voltage source on the negative input of the op-amp, it can be adjusted to change the width of the wave form.
