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For engineers in the electronics industry, electronic components need to be met every day and need to be used every day, but in fact, many engineers in the door are not necessarily aware of it. Here are the ten major electronic components commonly used by engineering teachers, and related basic concepts and knowledge.
1. Resistance
As a worker in the electronics industry, resistance is unknown. The importance of it is beyond doubt. People say that resistance is the most used component in all electronic circuits.
Resistance, because of the impediment of the substance to the electric current, is called the resistance substance under this action. Resistance will lead to changes in the amount of electronic flow, the smaller the resistance, the greater the amount of electronic flow, and vice versa. A substance with very little resistance or resistance is called an electric conductor, or a conductor. The substance that can not form the current transmission is called an electrical insulator, or an insulator.
In physics, the resistance (Resistance) is used to indicate the magnitude of the impediment of the conductor to the current. The greater the resistance of a conductor, the greater the impediment of the conductor to the current. Different conductors have different resistances. Resistance is a characteristic of the conductor itself. Resistive elements are energy dissipation elements that impede current.
The resistance value of the resistance element is generally related to the temperature. The physical amount of the resistance affected by the temperature is the temperature coefficient, which is defined as the percentage of the change of the resistance value when the temperature rises at 1 degrees centigrade.
The resistor is represented by "R" plus the number in the circuit, for example, R1 indicates a resistance of 1. The main functions of resistance in the circuit are shunting, current limiting, partial voltage, bias and so on.
Two. Capacitance
The capacitance (or capacitance, Capacitance) refers to the amount of charge stored under a given potential difference; it is recorded as C, and the international unit is Fala (F). In general, the charge is moved in an electric field. When a conductor has a medium, it prevents the charge from moving and accumulates the charge on the conductor; the most common example is the two parallel metal plates. It is also a common name for capacitors.
1, capacitance in the circuit is usually expressed in terms of "C" plus numbers (for example, C13 indicates capacitance of 13). Capacitance is composed of two metal films, which are separated by insulating materials in the middle. The main characteristics of the capacitance are the direct circulation and communication. The size of capacitive capacity means the size of the energy that can be stored. The impeding effect of capacitance on AC signals is called reactance, which is related to the frequency and capacitance of the AC signals. Resistance to XC=1/2 PI FC (F for the frequency of AC signals, C for capacitance capacity) the types of capacitors commonly used in the telephone are electrolytic capacitor, ceramic capacitor, patch capacitance, single stone capacitance, tantalum capacitor and polyester capacitor.
2, the identification method: capacitance recognition method and resistance identification method is basically the same, divided into direct mark method, color mark method and number mark method 3 kinds. The basic unit of capacitance is represented by Fala (F). Other units are: mF, uF, nF and pF.
Among them: 1 Fala =103 MS =106 micromethod =109 Nana method =1012 leather capacity large capacity capacity value on capacitance directly marked on capacitance, such as 10uF/16V capacity small capacity of capacitance its capacity value on capacitance with letters or numeric representation of letters: 1m=1000uF1P2=1.2PF1n=1000PF digital representation: generally using three digit numbers to express capacity size The first two figures are valid numbers, and the third digits are multiplying rates. For example, 102 means that 10 x 102PF=1000PF224 represents 22 x 104PF=0.22uF3, capacitance error meter symbol FGJKLM allowed error + 1% + 2% + 5% + 10% + 20% + 20%, such as a ceramic capacitor of 104J capacity 0.1uF, error of + 5%.
Three. Crystal diode
Crystal diode (crystaldiode) semiconductor devices at both ends of solid-state electronic devices. The main features of these devices are nonlinear current voltage characteristics. With the development of semiconductor materials and technology, various semiconductor materials, doping distribution and geometric structure have been developed, and many kinds of crystal diodes with various kinds of structure and different functional applications have been developed. The manufacturing materials are germanium, silicon and compound semiconductors. Crystal diodes can be used to generate, control, receive, transform, amplify signals and carry out energy conversion.
The crystal diode is commonly used in the circuit as "D" plus numeric representation, for example, D5 means diode with numbered 5.
1, function: the main characteristic of the diode is the unidirectional conductivity, that is, under the action of the forward voltage, the conduction resistance is very small, and the resistance is great or infinity under the action of the reverse voltage. Because of the characteristics of the diode, the cordless telephone often uses it in rectifying, isolating, stabilizing, polarity protection, coding control, FM modulation and static noise. The crystal diodes used in the telephone can be divided into rectifying diodes (such as 1N4004), isolated diodes (such as 1N4148), Schottky diodes (such as BAT85), light emitting diodes, and voltage regulated diodes.
2, identification method: the identification of the diode is very simple, the N pole (negative) of the small power diode, most of the diode appearance uses a color ring mark, some diodes also use the diode special symbols to express the P polar (positive) or the N pole (negative), and also use the symbol label "P", "N" to determine the polarity of the diode. The positive and negative poles of light emitting diodes can be identified from the length of pins. The long feet are positive and the short feet are negative.
3, test attention: when using digital multimeter to test the diode, the red pen connects the diode to the cathode, and the black pencil leads the negative electrode. At this time the measured resistance is the forward conduction blocking value of the diode, which is the opposite to the pointer type multimeter.