Converts 9 volt source to a 12 volt peak-to-peak square wave. In the oscillator stage, the different valued capacitors can change the frequency of the square wave. In the Op-amp stage, the power rail is set to +/- 6 volts with a negative feedback config. with multiplicity of 3. Thus, amplifying the oscillator signal from rail to rail. On the positive terminal of the Op-Amp is a voltage regulator configuration that will hold about 2.5 volts. This helps with the vertical shift of the final square wave. In this case, the 2.5 volts centers the square wave about the 0 volt axis
