Transistor Switching Operation - Lincoln Electric PRO-CUT 60 SVM104-A Service Manual

E-5
TRANSISTOR SWITCHING
OPERATION
A transistor is a solid state device consisting of
three layers of silicon crystal. These three layers
form the emitter, collector and base regions of a
transistor. They are used at high frequencies in
high power applications and switching circuits.
When used as a switch the transistor will be
"turned on" (collector current flow) when there is
PRO-CUT 60
THEORY OF OPERATION
FIGURE E.7 - Transistor Switching Operation
adequate base drive current. Likewise the device
will be "turned off" (no collector current) when
there is insufficient base drive current. The tran-
sistor allows the control of a large amount of cur-
rent flow through the collector and emitter with a
much smaller current in the base circuit.
Figure E.7.
See