. The first part of the circuit is an astable multivibrator. This will generate a square wave which will oscillate between positive and negative saturation. This square wave is passed on to an integrator. The integral of a constant say ‘c’ will be c*t where ‘t’ is time across which the integration is taken place. This means that a positive constant will give a positive ramp and a negative constant will integrate to a negative ramp. Adding them together we get a triangular wave. We got our square wave and triangular wave – if only there were a way to obtain a sine wave too from this setup. Well there is. What will happen if you integrate the above triangular wave? A triangle wave consists of positive and negative going ramps. A ramp is a function that increases linearly with time. If you integrate a ramp, you get a function that increases as the square of time which has the shape of a parabola. So the integral of a triangle wave is a series of positive and negative going parabolic shapes. In other words, yes you guessed it right you will get a pretty accurate sine wave. Alternatively I can approach this mathematically. We have to integrate the ramp c*t – which would result in c*t2/2. As you can see integration reduces the amplitude of the result. This can be adjusted by inserting an amplifier at the end.