电子元器件的作用

电子元器件的作用 Diagrams and functions of common electronic components In electronic making, many different electronic components are used. In this section, you will briefly introduce the commonly used electronic components. The role of the students should know them, understand them, remember their symbols, in order to facilitate the future application of these components assemble all kinds of useful and interesting electronic products. One, resistor and capacitor (1) resistor We connected the batteries, switches and lights with wires to the 3-1 circuit. When the switch closes, the current is flowing out of the battery, the switch and the light bulb go to the negative electrode, and the light bulb shines. Wires and light bulbs can conduct electricity. They are called conductors. In general, metals are conductors. When a conductor passes through a current, there is a certain resistance to the current, which is called resistance. The symbol for resistance is R. Ω size the basic unit of resistance is the ohm (symbol), and the larger units thousand Ω (K), and megohm Ω (M). Their conversion relationship is: 1 m Ω Ω Ω 1 k = 103 = 103 k Ω Figure 3-1 lamp circuit There are two main types of resistance. Fixed resistors are called fixed resistors. A variable resistor is known as a variable resistor (including an invid resistor and potentiometer). Their appearance and graphic symbols are shown in table 3, 1. Because of different materials, the resistor can be divided into carbon film resistance, metal film resistance, or wire wound resistance, etc. What does the resistor do in the circuit? Table 1 common resistor Fixed resistor trimming resistor potentiometer R R R We replace the switch in the 3-1 circuit with A 470 ohm potentiometer (figure 3, 1, 2 (A)). The rotation of the rotating potentiometer, the brightness of the small bulb will change as the resistances are resized. The bigger the resistance, the darker the light bulb. This shows that the resistor can control the strength of the current in the circuit. We can use this circuit to make a dimmer lamp. Figure 3-2 resistor and capacitor are used in the circuit The main parameters of the resistor are two: Nominal and permissible errors. The resistance value labeled on the resistance is called the nominal resistance. Such as 1.5 K, 5.1 Ω... It is. Its real value allows a certain error, name is permissible error, divided into ? level (+ / - 5%), grade ? (+ / - 10%), grade ? (plus or minus 20%). Such as resistor superscript "3 k Ω ?", said the resistance value is 3 k Ω, error is 5%. The nominal value and error of the resistance can also be represented by a ring of color. On the resistance, there are four colorful garden rings on the resistance, and three colored rings on the left side of the resistance are called the resistance value, and the final color ring indicates the permissible error. The recognition method is shown in table 3, 1, 2. The nominal value of the resistor and potentiometer is its maximum resistance value. For example, the 100K potentiometer indicates that its resistance can vary from zero to 100 kiloohm. Power rating. The maximum power permitted when the resistor is working properly. Over this value, the resistor will burn out too hot. In the electronic production involved in this chapter, the resistor adopts 1/8w carbon film resistance, such as no special requirement. (2) capacitor Two conductors that are insulated and close together form a capacitor. Two conductors are called the two poles of a capacitor, which are led out by a wire. The symbol for the capacitor is C. Its size is measured in terms of its capacity. The basic unit of electric capacity is a farad (represented by F), and the smaller unit microlaw (mu F) and the skin method (PF), these three units of conversion are: 1F = 106 mu F 1 mu F = 106PF Table two color ring notation color The first color ring The second color ring The third color ring The fourth color ring Ten digits Unit digit Times the multiplier Margin of error brown one one X 101 red 2 2 X 102 orange 3 3 X 103 huang 4 4 X 104 green 5 5 X 105 blue 6 6 X 106 The purple 7 7 X 107 grey 8 8 X 108 white 9 9 X 109 black 0 0 X (100). gold X 0.1 Plus or minus 5% silver X 0.01 Plus or minus 10% ecru Plus or minus 20 Capacitors can also be divided into fixed capacitors and variable capacitors according to their capacity. It can be divided into porcelain dielectric containers, electrolytic capacitors, air capacitors, and so on. The shape of the capacitor and the symbol are shown in table 3-3. Fixed capacitor Trimmer capacitors The variable capacitance C, C, C, C C What does the capacitor do in the circuit? We replace the switch in the figure 3-1 circuit with a capacitor (see figure 3-2 (B)). When we connected the circuit, we saw that the light bulb went off when it was shining. This is because the capacitor is in a moment of charge, and there is a current in the circuit. The charging process is quickly over, and the capacitor is charged and the current disappears. The smaller the capacitors, the shorter the time the charge will be, and the direct current can't be passed through the capacitor. If change the power supply to the ac power, small bulb will continue to shine, if the frequency of alternating current (ac) can change, so under the same voltage, high frequency alternating current (ac) with low frequency alternating current (ac) more easily through the same capacitor and make little more light bulb. These experiments can show that the capacitor is in the circuit, which can "connect", "pass high frequency, prevent low frequency". The main parameters of the capacitor are two: Nominal capacity and permissible error. Nominal capacitance refers to the amount of electrical capacity on a capacitor. The error is allowed three levels, the same as the resistor's error. Fine tuning capacitors and variable capacitors mark the minimum and maximum values of its electrical capacity, such as 7/270p Pressure resistance. The maximum voltage applied to the capacitor when the capacitor is working properly. Do not exceed, otherwise will damage capacitor. In particular is electrolytic capacitor poles have positive and negative, there is a polar capacitor, must be in accordance with the requirements of circuit access, not be able to pick up the two pin. Skills training knows resistor and capacitor Objective to recognize resistors and capacitors and to identify resistance and error of color ring resistance. Equipment different specifications and types of resistors and capacitors. 10 different color ring resistance. steps Identify resistors of different specifications and types and read resistor's nominal resistance and error. Recognize different sizes and types of capacitors, read capacitor's nominal capacity and error. Place 10 color ring resistance on the cardboard, observe color ring color (reference table 3-2), write the nominal value and error of each resistance. Students ask each other, 10 color ring resistance, how many do you recognize right? Transistors and integrated circuits Transistors and integrated circuits are often used in electronic production. Transistors are divided into crystal diodes and transistors, which are made of semiconducting materials, so they are also called semiconductor tubes. (1) crystal diode The symbol for a crystal diode is VD, and its shape and graphic symbols are shown in table 3-4. Table 4 commonly used diodes Detector diode Rectifier diode Light-emitting diodes (leds) photodiode What does a diode do in a circuit? We take the diode to the switch position in the diagram 3-1 circuit (figure 3-3 (A)). The bulb lights up, indicating that the diode is conductive, and the resistance of the diode (called the positive resistance) is small. When the diodes are tuned (as in figure 3-3 (B)), the light bulb doesn't light up. At this point, the diode's resistance (called the reverse resistance) is large, and there is little current in the circuit. This phenomenon indicates that diodes have a characteristic of one-way conduction. Using this feature of the diode, the diode can be used for detection and rectifier. The one-way conductivity of the crystal diode Crystal diodes have two parameters: Maximum forward current: the maximum current allowed through the diode. Maximum reverse voltage: the maximum voltage applied to the diode when the diode is off. The above two parameters cannot exceed in use, otherwise the diode will be damaged. Other special USES, such as photodiodes and leds, are also used in electronic production. (2) transistor triode The transistor is also made of semiconductor materials, which are divided into PNP and NPN types. The triode symbol is V. Common triode shapes and graphic symbols such as table 3-5. Table 3-5 is a common triode PNP NPN The three poles of the transistor are called the base (b), collector (c) and emitter (e). The arrow on the emitter indicates the current direction of the triode. The flow of current in the two types of triode is the opposite. The transistor has an amplification and switch in the circuit. We use crystal triode to amplify the weak signal current in the circuit or to make an automatic switch that controls the power of the circuit breaker. Crystal triode works in a more complicated way, not to be introduced here. The main parameters of triode are the penetrating current and magnification. The smaller the current Iceo, the better the stability of the triode. The magnification beta typically starts from a few decades to a few hundred, and should be chosen according to the circuit. (3) integrated circuits Integrated circuit is the diode, triode and resistance capacitance component according to the requirements of the circuit structure, production on a small piece of semiconductor material, has a certain function of form a complete circuit, and encapsulation. Its characters are IC, and the form and graphic symbols of the common integrated circuit are shown in table 3-6. Table 3-6 common integrated circuits The integrated circuit was developed rapidly in the late 1960s with the development of electronic technology. Using integrated circuits and circuits assembled using discrete components, there are many advantages such as low component, light weight, small volume, good performance and power saving. So the integration of electronic products has become an inevitable trend of electronic technology development. In this chapter, we will use the integrated circuit, which students can experience in practice. Skills training knowledge of transistors and integrated circuits Objective to recognize transistors and integrated circuits Device crystal diode 2AP9 2CPI0 1N4001 Crystal triode 3DG6, 3A, 3A, 9013 Integrated circuit LM386 kd-9300, etc