summary of bipolar Transistors

summary

A transistor is a three-layer device used to amplify and switch power and voltage.

● A bipolar transistor is also called a junction transistor or simply a transistor.

● Transistors can be configured as NPN or PNP.

● The middle region of the transistor is called the base, and the two outer regions are called the emitter and collector.

● The schematic symbols used for NPN and PNP transistors are

● Transistors are identified with a prefix of 2N followed by up to four digits.

● The transistor package provides protection, a heat sink, and a support for the leads.

● Transistor packages are identified with the letters TO (transistor outline).

● In a properly biased transistor, the emitter-base junction is forward biased and the collector-base junction is reverse biased.

● PNP transistor bias sources are the reverse of NPN bias sources.

● The internal barrier voltage for germanium transistors is 0.3 V and for silicon transistors is 0.7 V.

collector-base junction is higher than the forward-bias voltage applied to the emitter-base junction.

● When a transistor is tested with an ohmmeter, each junction exhibits a low resistance when it is forward biased and a high resistance when it is

● A transistor is classified according to whether it is NPN or PNP, silicon or germanium, high or low power, and switching or high frequency.

reverse biased.

● Transistor testers are available for testing transistors in and out of circuit.

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