For engineers engaged in the electronics industry, electronic components, like people's daily imports of rice, is the need to contact every day, every day need to use, but in fact, many engineers may not understand the doorways inside. Here is a list of the top ten electronic components commonly used by engineers, and the related basic concepts and knowledge, and everyone together to review it.
1. resistors
As workers in the electronics industry, resistors are unknown to everyone. Its importance, there is no doubt. People say that "resistance is the most used component in all electronic circuits."
A resistor is a resistive substance that acts as a barrier to electric current. Resistance causes a change in the amount of electron flow, and the lower the resistance, the greater the amount of electron flow, and vice versa. A substance that has no resistance or very little resistance is called an electrical conductor, or conductor for short. A substance that cannot form an electric current transmission is called an electrical insulator, or insulator for short.
In physics, resistance is used to express the magnitude of a conductor's effect on the impediment of electric current. The higher the resistance of a conductor, the greater the impedance of the conductor to the current. The resistance is generally different for different conductors, and resistance is a characteristic of the conductor itself. A resistive element is an energy dissipating element that presents an impeding effect on current.
The size of the resistance of a resistive element is generally related to the temperature. The physical quantity that measures the size of the resistance affected by temperature is the temperature coefficient, which is defined as the percentage change in resistance value for each 1°C increase in temperature.
Resistance in the circuit is expressed by "R" plus a number, such as: R1 means the number of 1 resistance. The main role of the resistor in the circuit for shunt, current limiting, voltage divider, bias, etc.
1, the identification of parameters: the unit of resistance for the ohm (Ω), multiplier units are: kilo-ohm (KΩ), megohm (MΩ), etc.. Conversion method is: 1 megohm = 1000 kilohm = 1,000,000 ohms resistor parameters labeling method has three kinds, namely, the straight label method, color label method and number label method. a, number label method is mainly used for SMD and other small volume of the circuit, such as: 472 said 47 × 100Ω (that is, 4.7K); 104 said 100K b, color ring label method is used most, now the following examples: four color ring resistor five color ring resistor (precision resistors).
2, the resistor color scale position and multiplier relationship is shown in the following table: color effective number multiplier allowable deviation (%) silver/x0.01±10 gold/x0.1±5 black 0+0/brown 1x10±1 red 2x100±2 orange 3x1000/yellow 4x10000/green 5x100000±0.5 blue 6x1000000±0.2 purple 7x10000000±0.1 gray8x100000000/white9x1000000000/.
2. Capacitance
Capacitance refers to the amount of charge stored at a given potential difference; noted as C, the international unit is Farad (F). Generally speaking, the charge will be moved by force in the electric field, when there is a medium between the conductors, it prevents the charge from moving and makes the charge accumulate on the conductor; causing the accumulation of charge storage, the most common example is two parallel metal plates. It is also the common name of capacitor.
1、Capacitance is generally expressed by "C" plus a number in the circuit (e.g., C13 means the capacitor numbered 13). Capacitor is a component composed of two metal films close to each other and separated by insulating material. The characteristic of capacitor is mainly to separate the direct current. The size of capacitance is the size of the electrical energy that can be stored, and the obstruction of the AC signal by the capacitor is called the capacitive resistance, which is related to the frequency and capacity of the AC signal. Capacitive resistance XC=1/2πfc(f indicates the frequency of AC signal, C indicates the capacitance capacity) The types of capacitors commonly used in telephones are electrolytic capacitors, porcelain chip capacitors, chip capacitors, monolithic capacitors, tantalum capacitors and polyester capacitors. Please visit: transmission and distribution equipment website for more information
2、Identification method: The identification method of capacitor is basically the same as that of resistor, which is divided into 3 kinds: direct label method, color label method and number label method. The basic unit of capacitance is Farad (F), other units are: millifarad (mF), microfarad (uF), nanofarad (nF), pifarad (pF). Among them: 1 Farad = 103 mF = 106 microfarads = 109 nanofarads = 1012 picofarads The capacity value of capacitor with large capacity is marked directly on the capacitor, such as 10uF/16V Capacitor with small capacity is expressed by letters or numbers on the capacitor Letter expression: 1m=1000uF1P2=1.2PF1n=1000PF Digital expression: generally three numbers are used The first two digits indicate the effective number and the third digit is the multiplier. For example: 102 means 10×102PF=1000PF224 means 22×104PF=0.22uF3, capacitor capacity error table symbol FGJKLM allows error ±1%±2%±5%±10%±15%±20%For example: a porcelain chip capacitor is 104J means capacity is 0.1uF, error is ±5%.
3. crystal diode
Crystal diodes are semiconductor two-terminal devices in solid-state electronic devices. The main characteristic of these devices is that they have nonlinear current-voltage characteristics. Since then, with the development of semiconductor materials and process technology, a wide variety of crystal diodes with various structures and functional uses have been developed using different semiconductor materials, doping distributions, and geometric structures. The manufacturing materials are germanium, silicon, and compound semiconductors. Crystal diodes can be used to generate, control, receive, transform, amplify signals and perform energy conversion.
Crystal diode in the circuit commonly used "D" plus the number, such as: D5 said the number of 5 diodes.
1, the role: the main characteristic of the diode is a one-way conductivity, that is, in the forward voltage under the action of the on-resistance is very small; and in the reverse voltage under the action of the on-resistance is very large or infinity. Because the diode has the above characteristics, the cordless phone is often used in rectification, isolation, voltage regulation, polarity protection, coding control, FM modulation and quiet noise circuit. Telephone in the use of crystal diodes can be divided according to the role: rectifier diode (such as 1N4004), isolation diode (such as 1N4148), Schottky diode (such as BAT85), light-emitting diode, voltage regulator diode, etc..
2, identification method: diode identification is very simple, low power diode N pole (negative), in the diode appearance mostly using a color circle marked out, some diodes also use the diode special symbol to indicate the P pole (positive) or N pole (negative), there is also the use of symbols marked as "P", " N" to determine the polarity of the diode. Light-emitting diode positive and negative can be identified from the pin length, the long leg is positive, short leg is negative.
3, test notes: digital multimeter to test the diode, the red pen connects the positive terminal of the diode, the black pen connects the negative terminal of the diode, the measured resistance value is the positive conduction resistance value of the diode, which is the opposite of the pointer multimeter pen connection.
4, commonly used 1N4000 series diode voltage withstand comparison as follows: Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007 voltage withstand (V) 50 100 200 400 600 800 1000 current (A) are 1.
5. voltage regulator diodes
Voltage regulator diode (also called Zener diode), this diode is a semiconductor device with high resistance until the critical reverse breakdown voltage. Voltage regulator diode in the circuit commonly used "ZD" plus the number, such as: ZD5 that the number of 5 voltage regulator.
1, the voltage regulator diode principle: the voltage regulator diode is characterized by breakdown, the voltage at both ends of the basic remains unchanged. In this way, when the voltage regulator is connected to the circuit, if the voltage fluctuations due to the power supply, or other reasons caused by changes in the circuit voltage at various points, the voltage across the load will remain basically unchanged.
2, fault characteristics: the failure of the voltage regulator diode is mainly manifested in open circuit, short circuit and voltage regulator value is unstable. In these three kinds of faults, the former fault shows the power supply voltage rise; the latter two faults show that the power supply voltage becomes low to zero volts or output instability. Commonly used voltage regulator diode model and voltage regulator value is as follows: Model 1N4728 1N4729 1N4730 1N4732 1N4733 1N4734 1N4735 1N4744 1N4750 1N4751 1N4761 voltage regulator value 3.3V 3.6V 3.9V 4.7V 5.1V 5.6V 6.2V 15V 27V 30V 75V.
6. Inductance
Inductance: When a coil passes a current, a magnetic field is induced in the coil, and the induced magnetic field in turn generates an induced current to *restrain the current through the coil. We call this interaction between the current and the coil the electrical inductance, or inductance, in units of "Henry" (H). This property can also be used to make inductive components.
Inductance is often expressed in the circuit by "L" plus a number, e.g., L6 means the inductance number is 6. An inductor coil is made by winding an insulated wire around an insulated skeleton for a certain number of turns. DC can be passed through the coil, DC resistance is the resistance of the wire itself, the voltage drop is very small; when the AC signal through the coil, the coil ends will produce self-inductance electromotive force, the direction of self-inductance electromotive force and the direction of the applied voltage is opposite to impede the passage of AC, so the characteristics of the inductor is through DC resistance AC, the higher the frequency, the greater the coil impedance. The higher the frequency, the higher the coil impedance. Inductors can be used in circuits with capacitors to form oscillating circuits. Inductors generally have a direct method and color-coded method, color-coded method and resistance similar. For example: brown, black, gold, gold indicates 1uH (error 5%) of inductance. The basic unit of inductance is: Hen (H) conversion units are: 1H = 103mH = 106uH.
Six: variable capacitance diode
Varactor diodes (VaractorDiodes) is also known as "variable reactance diodes". Is a kind of PN junction capacitance (barrier capacitance) and its reverse bias voltage Vr dependence and the principle of diodes made.
Tube varactor diode is a special diode designed according to the principle that the junction capacitance of the "PN junction" inside the ordinary diode can change with the applied reverse voltage. Varactor diodes are mainly used in cordless phones in the high frequency modulation circuit of cell phones or landlines to achieve low frequency signal modulation to high frequency signal and transmit out. In the operating state, varactor diode modulation voltage is generally added to the negative pole, so that the internal junction capacitance capacity of the varactor diode changes with the modulation voltage. Variable capacitance diode failure, mainly for leakage or performance deterioration: (1) leakage phenomenon occurs, the high frequency modulation circuit will not work or modulation performance deterioration. (2) varactor performance deterioration, the work of high-frequency modulation circuit is not stable, so that the modulated high-frequency signal sent to the other side is received by the other side to produce distortion. When one of the above situations, you should replace the same type of varactor diode.
7. crystal transistor
Crystal transistor, one of the basic semiconductor components, with current amplification, is the core component of electronic circuits. Triode is a semiconductor substrate to produce two PN junctions close to each other, two PN junctions to the semiconductor is divided into three parts, the middle part is the base area, the two sides of the part is the emission area and collector area, the arrangement of PNP and NPN two.
Crystal transistor in the circuit commonly used "Q" plus the number said.
1, characteristics: crystal transistor (referred to as transistors) is a special device containing two PN junctions inside, and has the ability to amplify. It is divided into NPN type and PNP type two types, these two types of transistors from the working characteristics of each other to make up for the so-called OTL circuit is the pair of PNP type and NPN type paired use. Telephone in the commonly used PNP-type transistors are: A92, 9015 and other models; NPN-type transistors are: A42, 9014, 9018, 9013, 9012 and other models.
2, the crystal transistor is mainly used in the amplification circuit to play an amplifying role in the common circuit there are three kinds of connection. In order to facilitate comparison, the characteristics of the three transistor connection circuits are listed in the following table for your reference. Name common emitter circuit common collector circuit (emitter output) common base circuit input impedance in (hundreds of ohms ~ thousands of ohms) large (tens of thousands of ohms above) small (a few ohms ~ tens of ohms) output impedance in (thousands of ohms ~ tens of thousands of ohms) small (a few ohms ~ tens of ohms) large (tens of thousands of ohms ~ hundreds of thousands of ohms) voltage amplification multiplier size (less than 1 and close to 1) large current amplification multiplier large (tens) large (tens) small (less than 1 and close to 1) power amplification times large (about 30 ~ 40 db) small (about 10 db) in (about 15 ~ 20 db) frequency characteristics of high-frequency differential good continued table application of multi-stage amplifier intermediate stage, low-frequency amplification input stage, output stage or for impedance matching with high-frequency or wide-band circuit and constant-current source circuit.
8. field effect tube
Field effect transistor (FieldEffectTransistor abbreviation (FET)) is referred to as the field effect tube. Conducted by the majority of carriers involved, also known as unipolar transistors. It is a voltage-controlled semiconductor device. With high input resistance (108 ~ 109Ω), low noise, low power consumption, dynamic range, easy to integrate, no secondary breakdown phenomenon, safe working area wide and other advantages, has become a strong competitor of bipolar transistors and power transistors.
1, field effect transistor has the advantages of high input impedance and low noise, thus it is also widely used in various electronic devices. Especially with the field-effect tube as the input stage of the whole electronic equipment, you can get the performance that is difficult to achieve with general transistors.
2、Field-effect tubes are divided into two categories: junction type and insulated gate type, whose control principles are the same. Such as Figure 1-1-1 is the symbol of the two types of representation.
3, the field effect tube and transistor comparison
(1) Field effect tube is a voltage control element, while the transistor is a current control element. In the case where only less current is allowed to be taken from the signal source, the field effect tube should be used; and in the case where the signal voltage is lower and more current is allowed to be taken from the signal source, the transistor should be used.
(2) Field effect tube is the use of most carriers conductive, so called unipolar devices, while the transistor is that there are most carriers, but also the use of a few carriers conductive. They are called bipolar devices.
(3) The source and drain of some FETs can be used interchangeably, and the gate voltage can be positive or negative, which is more flexible than transistors.
(4) FETs can work at very small currents and very low voltages, and its manufacturing process can easily integrate many FETs on a silicon wafer, so FETs are widely used in large-scale integrated circuits.
9. sensor
A sensor is a physical device or biological organ that can detect and feel the external signal, physical conditions (such as light, heat, humidity) or chemical composition (such as smoke), and will detect the information transmitted to other devices or organs.
National standard GB7665-87 on the sensor under the definition is: "can feel the specified measured parts and in accordance with certain laws into the available signal devices or devices, usually composed of sensitive elements and conversion elements." The sensor is a detection device, can feel the measured information, and can detect the information felt, according to certain laws into electrical signals or other required forms of information output to meet the requirements of information transmission, processing, storage, display, recording and control. It is the first link to achieve automatic detection and automatic control.
10. Transformer
Transformer is a device that uses the principle of electromagnetic induction to change the AC voltage, the main components are the primary coil, secondary coil and iron core (core). In electrical equipment
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