The schematic shown below diagrams the emitter follower circuit using 2N3904, an NPN silicon bipolar junction transistor. In the circuit provided, input signal is applied to the base of the transistor, but the output is taken from the emitter.Instead of using 2N3904 transistors, this emitter follower circuit uses such parameters: 40V collector to emitter voltage (Vce), 6V emitter to base voltage (Veb), 200mA collector current (Ic), 300mW power dissipation (Pmax), 300Mhz frequency where internal capacitances cause gain to be reduced to unity (fT), 10pF internal emitter-base capacitance (Ceb), and 3pF internal base-collector capacitance (Cbc).
Here, if you need to read the 2N3904 datasheet
