This circuit is a two-stage microphone amplifier that is equipped with an Emitter Follower Amplifier. The second stage provides no voltage gain. However, it provides current gain such that it can drive a mixer in a transmitter.
This indicates that operational amplifiers are not always the stuff of legend, as some people think. In other words, it is also possible to use a BJT instead of an operational amplifier. By using a smaller circuit (rather than the hundreds of transistors contained within the black box), you can achieve remarkable results. First, you will be able to understand what the circuit does. The majority of 8-pin DIP-packaged operational amplifiers are equipped with two amplifiers, so it is sometimes necessary to discard one of them. You will also be able to lay this circuit out on a single sided printed circuit board with less hassle than with an 8 pin DIP package.
