At AboutMechanics, we're committed to delivering accurate, trustworthy information. Our expert-authored content is rigorously fact-checked and sourced from credible authorities. Discover how we uphold the highest standards in providing you with reliable knowledge.

Learn more...

What is the Collector Current?

Alexis W.
Alexis W.

A collector current is referred to when identifying the output current from the transistor to the transistor’s collector terminal. The collector current, along with the base current, is a product of the energy produced through the emitter circuit, which is divided at the base current’s generation through the transistor. Only a fraction of the exiting current is base current, and the remaining portion is considered the collector current. The collector current is always directly affected by the amount of base current from the beginning of the circuit.

If the transistor in the circuit produces a collector current the value of .03 amps, this represents the fact that the particular transistor in the circuit is acting as a conductor, with a forward bias voltage. This bias voltage is applied to the base current so a sufficient amount of base current flows to cause the transistor to produce sufficient collector currents. In a DC circuit, collector currents are based, for the most part, on the DC base current that is applied to the circuit and on the amplitude of the particular transistor in that circuit.


The current in a DC circuit is not directly applied to the specific collector current. DC voltage is applied, and as such, causes collector currents to be generated. The DC voltage then flows through the circuit and it is applied to the base current from the circuit’s transistor. It is important to note, however, that simply because a transistor is located within a circuit that has collector voltage along with base current measured at .03 amps, this doesn’t mean the collector current itself will be restricted to .03 amps or lower.

If any AC power signal is introduced at the base of the transistor, the base current will become varied according to the amplitude of the AC power signal. This will directly affect the collector current, raising it above and dropping it below .03 amps. Under these circumstances, the transistor in the circuit would become an amplifier.

If no AC power signal is introduced to the circuit, and the collector for the transistor is directly connected to a DC power signal, eliminating any AC signal by passing it through to ground out, then no AC signal can exist within the circuit. Even in this case, the collector current is still determined according to the DC base current being supplied to the transistor. It will fall to zero if the base voltage at the transistor doesn’t create a base current as well.

Discuss this Article

Post your comments
Forgot password?
    • Worker