I. Resistors and Capacitors (1) Resistors We connect batteries, switches, and bulb to Figure 3-1 circuit. After the switch is closed, the current flows from the battery positive electrode, flows into the battery negative by the switch and the small bulb, and the small light is luminous. Wires and small bulbs can be electrically conductive, which are called conductor. Metals are conductors in general. The conductor has a certain obstacle effect on the current when the current is passed, which is called the resistance. The text symbol of the resistor is R. The basic unit of the resistance is ohmic (symbolic), and there is a large unit of thousands of euros (KΩ), and Mega (MΩ). Their translational relationship is: 1MΩ = 103kΩ 1kΩ = 103Ω Figure 3-1 The electrical resistance commonly used in the lighting circuit is two categories. The resistor fixed resistor is referred to as a fixed resistor. The resistance of the resistance is called a variable resistor (including an emblem and potentiometer). Their shape and graphic symbols are shown in Table 3 1. Due to the different materials, resistors can also be divided into carbon film resistance, metal film resistance or wire resistance, and the like. What role does the resistor play in the circuit? Table common resistor
Fixed resistor fine adjustable resistor potentiometer R r r
We will change the switches in the circuit in Figure 3-1 to 1 470 ohm potentiometer (as shown in Figure 3 (a)). The handle of the rotating potentiometer, the brightness of the small bulb is to change as the magnitude of the resistance value. The larger the resistance value, the smashing the light bulb. This shows that the resistor can control the strength of the current in the circuit. We can refer to this circuit to make a dimming toy small lamp. Figure 3-2 The main parameters of the actuator and capacitors in the circuit are two: 1. Nominal resistance and allow error. The number of resistors marked on the resistor is called a nominal resistance. Such as 1.5k, 5.1Ω ....... Its actual resistance allows a certain error, called allowing errors, divided into level I (± 5%), II (± 10%), Class III (± 20%). If the resistor is marked "3kΩI", the resistance of this resistor is 3kΩ, and the error is 5%. The nominal value and error of the resistor can also be represented by the collar. Four colorful garden rings are printed on the resistor, and the three color circles on the left end of the electric resistance represent the resistance value, and the last color ring represents the allowable error. The identification method is shown in Table 3 2. The nominal value of the fine-tune resistor and potentiometer is its maximum resistance value. Such as a 100K potentiometer, indicating that its resistance can be continuously changed from zero to 100 kilo. 2. rated power. The maximum power allowed when the resistor is working properly. More than this value, the resistor will be overflow and burned. In the electronic production involved in this chapter, if there is no special requirement, the resistor uses 1/8 W carbon film resistance. (Ii) The capacitor is insulated from each other, and the conductor adjacent to each other constitutes a capacitor. The two conductor are called two poles of the capacitor, and they are drawn from the wires. The text symbol of the capacitor is C. Its size is measured by capacitance. The basic unit of the capacitance is Fara (rep to be used), and there is a smaller unit microfix (μF) and pepsin (PF), the translational relationship between these three units is: 1F = 106μF 1μF = 106PF Table color ring Notation
Color first color ring second color ring third color ring fourth color ring ten digits digits digital multiplier allowable error brown 1 1 × 101 red 2 2 × 102 orange 3 × 103 yellow 4 4 × 104 green 5 5 × 105 blue 6 6 × 106 purple 7 7 × 107 gray 8 8 × 108 white 9 9 × 109 black 0 0 × (100) gold × 0.1 ± 5% silver × 0.01 ± 10% color ± 20 capacitors can also be according to Whether the capacitance can be changed to a fixed capacitor and a variable capacitor. (Including the fine-tuning capacitor and variable capacitor) If the material is divided into a material, it can be divided into a porcelain capacitor, an electrolytic capacitor, an air capacitor, and the like. The shape and exhibit of the capacitor are in Table 3-3.
What is the role of fixed capacitors fine-tuning capacitor variable capacitance C C C C capacitor in the circuit? We use capacitors instead of the switches in the circuit of Figure 3-1 (as shown in Figure 3-2 (b)). When the circuit is turned on, we will not be bright after the light bulb is shining. This is because the capacitor is in an instant of charging, there is current in the circuit. The charging process is fast, and the current disappears after the capacitor is filled. The smaller the capacitance capacity, the shorter the time taken by the charge, and the visible DC is not passed through the capacitor. If the power is changed to an alternating power supply, the small bulb will continue to illuminate. If the AC frequency can vary, the high frequency alternating current is more likely to make the small bulb brighter by the same capacitor under the same voltage. These experiments can explain that the capacitor can function as "separation flow, communication", "high frequency, and low frequency". There are two main parameters of the capacitor: 1. Nominal capacity and allowance error. A nominal capacitance refers to the capacitance labeled on the capacitor. Allow the error of the error, the representation of the resistor error. The fine-tuning capacitor and variable capacitor marks the minimum and maximum values of its capacitance, such as 7 / 270p 2. Pressure. When the capacitor is operating normally, the highest voltage value is allowed to be applied to the capacitor. Can't exceed, otherwise the capacitor will be damaged. It is important to indicate that the electrolytic capacitor is positive and negative, there is a polar capacitor, and it must be accessed by circuitry when used, and two pins are not reversed. Skill training knows resistors and capacitors to recognize resistors and capacitors, learn to identify the resistance and errors of color loop resistance. Equipment different specifications and varies of resistors and capacitors. 10 different color ring resistors. step 1. Know the resistors of different specifications and types, read out the nominal resistance and error of the resistor. 2. Know different specifications and types of capacitors, read out the nominal capacity and error of the capacitor. 3. Insert 10 color ring resistors on the cardboard, observe the color loop color (Refer to Table 3-2), and write the nominal value and error of each resistor. 4. Classmates inspected each other, 10 color ring resistors, how many of you recognize correct? Second, transistors and integrated circuits use transistors and integrated circuits in electronic production. The transistor is divided into crystal diodes and crystal triodes, which are made of semiconductor materials, so it is also called semiconductor tubes. (1) The text symbol of the crystal diode crystal diode is VD, and its shape and graphic symbol are shown in Table 3-4. Table four common diodes
What is the role of the detection diode rectifier diode light emitting diode photodiode crystal diode in the circuit? Let the crystal diode are connected in the switch position in the circuit of Figure 3-1 (as shown in Figures 3-3 (a)). Lamp illuminates, indicating that the diode is turned on, and the resistance of the diode (called forward resistance) is small. If the diode pole pin is toned (as shown in Figure 3-3 (b)), the small light bulb is not bright. At this time, the resistance of the diode (referred to as a reverse resistance) is very large, and there is almost no current in the circuit. This phenomenon shows the characteristics of the diode with one-way conductive. This characteristics of the diode can be used to detect and rectify using a diode. Figure 3 The parameters of the one-way conductive crystal diode of the crystal diode have two: 1. Maximum forward current: The maximum current allows passage when the diode is turned on. 2. Maximum reverse voltage: The highest voltage of the diode is added when the diode is cut off. The above two parameters cannot exceed the use, otherwise the diode will be damaged. There are also some special use diodes, such as photodiodes, light emitting diodes, etc., are also often used in electronic production. (2) The crystal triode crystal triode is also made of a semiconductor material, and since the structure is divided into two categories: PNP type and NPN type. The text symbol of the triode is V. The shape and graphic symbols of commonly used triodes are shown in Table 3-5. Table 3-5 Three poles of commonly used triode PNP type NPN crystal triode are referred to as base (B), collector (C), and emitter (E). The arrow on the emitter indicates the direction of current flowing through the triode. It can be seen that the flow of current in the two types of triodes is the opposite. The crystal triode has an enlarged action and switching effect in the circuit. We use crystal triodes to enlarge weak signal currents in the circuit or make automatic switches, and control the power of electrical appliances. The working principle of crystal triodes is more complicated, and it is not described here. The main parameters of the triode are penetrating current and magnification. The smaller the penetration current Iceo, the better the triode stability. Laming a large multiple β generally from tens to hundreds, should be selected according to the circuit. (3) The integrated circuit integrated circuit is to create a small semiconductor material in a small semiconductor material in accordance with the requirements of the circuit structure, and form a complete circuit with a complete function, and then packaged. Its text symbol is an IC, and the shape and graphic symbol of the common integrated circuit are shown in Table 3-6. Table 3-6 Common integrated circuits
The integrated circuit is rapidly developed with the development of electronic technology in the late 1960s. With an integrated circuit and a circuit that uses a discrete component assembled, there is a number of components, light weight, small size, good performance and power saving. Therefore, the integration of electronic products has become an inevitable trend of electronic technology development. The integrated circuit will be used in the electronic production of this chapter, and students can experience its superiority in practice. Skill training knowledge transistors and integrated circuits have awareness transistor and integrated circuitry crystal diode 2AP9 2CPI0 1N4001 crystal triode 3DG6 3a × 31 9013 integrated circuit LM386 KD-9300 is equal to 1. Seriously observe the shape, model and pin distribution of transistors and integrated circuits. 2. The crystal triode pin is observed, distinguished B, C, E three poles and clarify the discrimination method.
