Voltage follower is generally used for amplify the current of a signal keeping the voltage same incase of driving high output loads (low resistance circuits).
[header= Simple Microphone amplifier]
8.4) Simple Microphone amplifier
Now let’s consider a complete voltage summing amplifier having capability of both voltage addition and subtraction. Input voltages are applied on both the inverting and non-inverting inputs.
So far we have seen some basic circuits using op-amp and I suggest the reader to go through the topics thoroughly. Practise as many circuits as possible. With each circuit you make you learn a new thing about the op-amp and your knowledge becomes more solid. Op-amp is an interesting electronic device and trust me you will enjoy making circuits with it!