The most recent installment of [Dino Segovis’] Hack a Week covers the construction of a simple NPN transistor audio preamp.Some time ago, he built a small audio amplifier using an LM386 which ...

Looking at the circuit diagram it follows the classic op-amp with a long-tailed pair of NPN transistors driving a PNP gain stage and finally a complimentary emitter follower as an output buffer.

The diagram illustrates the basic design of an NPN junction transistor ... which is how a transistor functions as an amplifier. It’s similar to the way you control the flow of water with ...