Transistor output, this is the statement in circuit control. In many automation equipment, the circuit ultimately needs to control some of the actuators (such as motors, electromagnets), the control of these components can be controlled by relays, triacs, transistors and other switching devices, so for the output of the circuit There are corresponding types of "relay output, bidirectional thyristor output, transistor output".
Transistor output characteristic curve (common emitter)
The transistor is composed of a three-part semiconductor forming two PN junctions, and its composition forms are PNP type and NPN type. The triodes produced in China are mostly PNP type, and the silicon triodes are mostly NPN type, and their structural principles are the same.
The triode has three zones and three electrodes. The base region (a thin semiconductor in the middle of the triode) leads to the base b; the emitter region on both sides leads to the emitter e and the collector region leads to the collector c. The PN junction between the emitter region and the base region is called the emitter junction, and the PN junction between the collector region and the base region is called the collector junction. On the circuit symbol, the PNP-type tube emitter arrow is turned inward, and the NPN-type tube emitter arrow is outward to indicate the current direction.