The so-called semiconductor refers to a substance whose electrical properties are between metal conductors and insulators, generally solids (such as germanium, silicon and certain compounds), in which the content of impurities and changes in external conditions (such as temperature changes, exposure to light, etc.) will cause Its conductivity changes.
At present, semiconductor components include: diodes, triodes, field effect transistors, thyristors, Darlington tubes, LEDs, and integrated blocks and chips containing semiconductor tubes.
① Diode:
Diode, (English: Diode), among electronic components, the most common function of diodes is to allow current to pass in only one direction (called forward bias) and block it in the reverse direction (called reverse bias). Therefore, diodes can be thought of as electronic versions of check valves.
② Triode:
An electronic component consisting of three electrodes. There are two kinds of tube triode and semiconductor triode. Electron tube triode consists of screen, grid and cathode; semiconductor triode consists of collector, base and emitter.
③ Field effect tube:
The field effect transistor is a voltage control element, which is similar to the triode of the electronic tube, but its structure and working principle are completely different from the electronic tube. Compared with the bipolar transistor, the field effect transistor has the following characteristics:
(1) The FET is a voltage control device, which controls ID through UGS;
(2) The input current of the FET is extremely small, so its input resistance is very large.
(3) It uses majority carriers to conduct electricity, so its temperature stability is better;
(4) The voltage amplification factor of the amplifier circuit composed of it is smaller than the voltage amplification coefficient of the amplifier circuit composed of triodes;
(5) The FET has strong anti-radiation ability;
(6) The noise is low because there is no shot noise caused by minority carrier diffusion of chaotic motion.
④ Thyristor:
The conduction condition of the thyristor is: the forward voltage is applied and the gate has a trigger current; its derived devices include: fast thyristor, bidirectional thyristor, reverse conducting thyristor, light-controlled thyristor, etc. It is a high-power switching semiconductor device, which is represented by the text symbols "V" and "VT" in the circuit (represented by the letters "SCR" in the old standard).
⑤ Darlington tube
Darlington tube principle: Darlington tube is also called composite tube. It properly connects two triodes together to form an equivalent new triode. This is equivalent to the magnification of the triode being the product of the two. Applications of Darlington tubes:
(1) It is used for high-power switching circuits, motor speed regulation, and inverter circuits.
(12 Driving small relays A circuit that uses CMOS circuits to drive high-sensitivity relays through Darlington tubes, as shown in the upper right figure. Inside the dashed box is a low-power NPN Darlington tube FN020.
(3) Drive LED smart display
⑥ LED diode
Light Emitting Diode (LED) is a semiconductor component. At the beginning, it was mostly used as an indicator light, a display light-emitting diode board, etc.; with the emergence of white LEDs, it was also used as lighting.
LED is called the fourth-generation lighting source or green light source. It has the characteristics of energy saving, environmental protection, long life and small size. It is widely used in various fields such as indication, display, decoration, backlight, general lighting and urban night scenes.
The above is a brief summary of several commonly used semiconductor electronic components, which are widely used in the field of electronics, and you can understand them.