COMMON COLLECTOR CONFIGURATION

Another transistor circuit configuration is common collector configuration as shown below...

simple common collector circuit

This circuit is basically same as the circuit of common emitter circuit with the exception that the load resistor (RL=RE) is in the emitter circuit rather than in the collector circuit. If we continue to specify the operation of the circuit in terms of the currents which flow, the operation of the common collector is much the same as for the common emitter configuration. when the base current is Ico, the emitter current will be zero, and no current will flow in the load. as the transistor is brought out of this back-biased condition by increasing the active region and eventually reach saturation. in this condition all the supply voltage , except for a very small drop across the transistor, will appear across the load.