Toes Are Red And Itchy Little Circulation

TRANSISTOR TRANSISTOR TYPES

• NPN TRANSISTOR

NPN is one of the two types of bipolar transistors, in which the letters "N" and "P" refers to the majority charge carriers in different regions of the transistor. Most bipolar transistors used today are NPN, because the electron mobility is greater than the mobility of the "holes" in semiconductors, allowing higher currents and operating speeds.

NPN Transistors consist of a layer of semiconductor material doped P (the "base") between two layers of doped N. A small current entering the base common-emitter configuration is amplified in the collector output.

The arrow in the NPN transistor symbol is on the emitter terminal and pointed in the direction that conventional current runs when the device is in active operation.

• PNP TRANSISTOR

The other type of bipolar junction transistor is a PNP with the letters "P" and "N "referring to the majority loads in different regions of the transistor. Few transistors used today are PNP, since the NPN provides much better performance in most circumstances.

PNP transistors consist of a layer of semiconductor material doped N between two layers of doped P. PNP transistors are commonly operated with the collector to ground and the emitter connected to the positive terminal of the power supply through an external electrical load. A small stream flowing from the base allows a much larger current flow from the emitter to the collector.

The arrow on the PNP transistor is the emitter terminal and pointed in the direction that conventional current runs when the device is in active operation.