A high level of efficiency can be achieved if the base voltage of the emitter remains at -5V.As you can see, the part has a transition frequency of 200MHz.A maximum collector current of 600mA volts is possible.
2N2904A Features
the emitter base voltage is kept at -5V a transition frequency of 200MHz
2N2904A Applications
There are a lot of Central Semiconductor 2N2904A applications of single BJT transistors.