c. The transistor regulator is a completely static unit containing no
moving parts. It performs only one function in the charging circuit--to limit the
generator voltage to a safe, preset value.
(1) A transistor is a device made of semiconductors.
They can be large
or small in size, depending upon the power they must handle.
(a) The symbol shown in figure 39 represents the electrical drawing
of a transistor. It consists of a device with three leads which are the EMITTER,
BASE, and COLLECTOR.
Figure 39.
Transistor ON.
(b) Essentially, the transistor is a variable resistor whose
resistance between emitter and collector is controlled by the current in the base
lead (fig 40).
Figure 40.
Variable resistor.
(c) The arrow on the emitter depicts a diode Junction between the
base and the emitter, which is the controlling path of current for the transistor.
(d) If this diode junction between the emitter and base is forward
biased, the resistance between the emitter and collector will be reduced.
(e) With a high value of forward bias current, the resistance
between the emitter and collector approaches zero allowing maximum current flow.
The transistor is said to be ON when forward biased.
OS 010, 1-P21
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