Transistor BC548 (50 pack). BC548 is an NPN epitaxial silicon transistor. It is mostly used for current amplification and switching. It has three terminals namely emitter, base, and collector. The amount of current flowing from base to the emitter controls the amount of the current flowing through the collector.BC548 has a gain value of 110 to 800. For the transistor in the saturation region, the maximum collector current is 100mA when the base current is limited to 5mA. Typically voltages allowed across the collector-emitter(VCE) are 200mV and across base-emitter(VBE) is 900mV. For the transistor in the cutoff region, the voltage across base-emitter(VBE) is around 660mV.