Transistor Structure Type

The crystal transistor is to make two PN junctions close to each other on a semiconductor substrate. The two PN junctions divide the whole semiconductor into three parts, the middle part is the base area, and the two sides are the emission area and the collector area. The arrangement methods are PNP and NPN.

The corresponding electrodes are introduced from the three regions, namely, base b emitter e and collector c.

The PN junction between the transmitting region and the base region is called the transmitting junction, and the PN junction between the collecting region and the base region is called the collecting junction. The base area is very thin, while the emission area is thick and the impurity concentration is high. The emission area of PNP type triode "emits" holes, whose moving direction is consistent with the current direction, so the emitter arrow is inward; The emission area of NPN type triode "emits" free electrons, and its moving direction is opposite to the current direction, so the emitter arrow is outward. The emitter arrow points to the conduction direction of the PN junction under the forward voltage. Silicon triode and germanium triode have PNP type and NPN type.

Packaging form and pin identification of triode

The commonly used triode packaging forms include metal packaging and plastic packaging. The pin arrangement has certain rules,

The bottom view is placed so that the three pins form the vertex of the isosceles triangle, which is e b c from left to right; For medium and small power plastic triode, make its plane face itself as shown in the figure, and place the three pins downward. Then, from left to right, it is Ebc.

There are many kinds of crystal triodes of various types in China. The arrangement of pins is different. For a triode with uncertain pin arrangement in use, it is necessary to measure and determine the correct position of each pin, or look up the transistor manual to clarify the characteristics of the triode and the corresponding technical parameters and information