Practical Transistor Amplifier The below fig shows a practical single stage transistor amplifier. The various circuit elements and their functions are described below. Practical Transistor Amplifier 1. Biasing Circuit: The resistor R 1, R 2, and R E form the biasing and stabilization circuit. 2. Input Capacitor C in : An electrolytic capacitor C in is used to couple the signal to the base of the transistor. The capacitor C in allows only a.c. signal to flow but isolates the signal source from R 2 . If it is not used, the signal source resistance will come across R 2 and thus change the bias. Typical value of C in is 10µF. 3. Emitter Bypass Capacitor C E : An emitter bypass capacitor C E is used in parallel with R E to provide a low reactance path to the amplified a.c. signal. If it is not used, then amplified a.c. signal flowing through R E will cause a voltage drop across i...