ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 2
enters the base as base current (IBB). At the same time, an
electron leaves the negative terminal of the battery, another
electron leaves the emitter as IE (creating a new hole) and
enters the positive terminal of VBB. Meanwhile, in the collector
circuit, electrons from the collector battery (VCC) enter the
collector as IC and combine with the excess holes from the base.
For each hole that is neutralized in the collector by an
electron, another electron leaves the emitter and starts its way
back to the positive terminal of VCC.
FIGURE 95. PNP TRANSISTOR OPERATION.
Although current flow in the external circuit of the PNP
transistor is opposite in direction to that of the NPN
transistor, the majority carriers always flow from the emitter
to the collector. This flow of majority carriers also results
in the formation of two individual current loops within each
transistor. One loop is the basecurrent path and the other
loop the collector current path. The
132
Previous Page
