Basic knowledge of circuit design (I)

Basic knowledge of circuit design

Basic knowledge of circuit design (I) Basic knowledge of circuit design (1)-Resistance The blocking effect of the conductive body on the current is called resistance, expressed by the symbol R, in the unit of Ohm, qianou, and zhaoou, respectively expressed by Ω, kΩ, and MΩ. I. Method for naming resistance models: The domestic resistor model consists of four parts (not applicable to sensitive resistors) The first part is the main name, which is represented by letters, indicating the product name. For example, R indicates resistance, and W indicates potentiometer. Part 2: material, represented by letters, indicating the material composition of the Resistance body, t-carbon film, H-composite carbon film, S-organic solid, n-inorganic solid, J-metallic film, Y-nitrogen film, C-deposition film, I-glass glaze film, X- winding. Part 3: classification, which is generally represented by numbers. For an individual type, it is represented by a letter, indicating the type of the product. 1-common, 2-common, 3-UHF, 4-high resistance, 5-high temperature, 6-precision, 7-precision, 8-high pressure, 9-special, G-high power, t-adjustable. Part 4: serial number, expressed in numbers, indicating different varieties of similar products to differentiate the product's exterior dimensions and performance indicators Example: r t 1 Type 1 ordinary carbon film Resistance A1} Ii. Classification of Resistors 1. Wire Wound resistors: General wire wound resistors, precision wire wound resistors, high-power wire wound resistors, and high-frequency wire wound resistors. 2. Film Resistors: carbon film resistors, composite carbon film resistors, metal film resistors, metal oxide film resistors, chemical deposition film resistors, glass glaze film resistors, and metal nitride film resistors. 3. Solid resistors: solid Carbon Resistors are synthesized in inorganic form and solid Carbon Resistors are synthesized in organic form. 4. sensitive Resistors: varistor, thermistor, photosensitive resistor, force-sensitive resistor, gas-sensitive resistor, and wet-sensitive resistor. Iii. Main feature parameters 1. nominal resistance value: the resistance value marked above the resistor. 2. allowable error: the percentage deviation between the nominal resistance value and the actual resistance value and the nominal resistance value, which indicates the accuracy of the resistor. The correspondence between allowable errors and accuracy levels is as follows: ± 0. 5%-0.05, ± 1%-0.1 (or 00), ± 2%-0.2 (or 0), ± 5%-I, ± 10%-II, and ± 20%-III 3. Rated Power: the normal atmospheric pressure is 90-106.6kpa and the ambient temperature is-55 ℃ ~ + The maximum power dissipation allowed by the long term operation of the resistor at 70 ℃. The rated power series of wire wound resistors is (W ): 1/20, 1/8, 1/4, 1/2, 1, 2, 4, 8, 10, 16, 25, 40, 50, 75, 100, 150, 250, 500 Rated power series of non-wirewound resistors: 1/20, 1/8, 1/4, 1/2, 1, 2, 5, 10, 25, 50, 100 4. Rated voltage: the voltage is calculated based on the resistance value and rated power. 5. Maximum operating voltage: maximum continuous operating voltage allowed. The maximum operating voltage is low during low-pressure operation. 6. temperature coefficient: the relative change of the resistance value caused by each temperature change of 1 ℃. The smaller the temperature coefficient, the better the resistance stability. The resistance increases with the increase of temperature to the positive temperature coefficient, and vice versa. 7. aging coefficient: the percentage of relative changes in resistance of a resistor at rated power under long-term load. It represents the duration of the resistor. 8. Voltage coefficient: within the specified voltage range, each voltage changes by 1 V, and the relative variation of the resistor. 9. Noise: an irregular voltage fluctuation in the resistor, which includes two parts: thermal noise and current noise. The thermal noise is caused by irregular electronic free motion in the conductor, irregular voltage variation at any two points on the conductor. Iv. Method for marking resistor Resistance 1. direct labeling: Numbers and Unit symbols are used to mark the resistance value on the resistor surface. The allowable error is expressed as a percentage directly. If no deviation is injected on the resistor, the deviation is ± 20%. 2. Text symbol method: Regular combination of Arabic numerals and text symbols to represent the nominal resistance value. The allowable deviation is also expressed by text symbols. The number before the symbol indicates the integer resistance value, and the number after the symbol indicates the first decimal resistance value and the second decimal resistance value. Text symbols indicating allowable errors Text symbol d f g j k m Allowable Deviation ±0. 5% ± 1% ± 2% ± 5% ± 10% ± 20% 3. Digital method: the method of marking the nominal value with three digits on the resistor. The number ranges from left to right. The first and second digits are valid values, and the third digit is an index, that is, the number of zeros, in Europe. The deviation is usually represented by a text symbol. 4. Color labeling: Mark the nominal resistance value and allowable deviation on the resistor surface with band or point in different colors. Most foreign resistors use the color standard method. Black-0, brown-1, red-2, orange-3, yellow-4, green-5, blue-6, purple-7, gray-8, white-9, gold-± 5%, silver-± 10%, colorless-± 20% When the resistance is four rings, the last ring must be golden or silver. The first two digits are valid numbers, the third digit is the multiplication square, and the fourth digit is the deviation. When the resistance is five rings, the last ring is far from the first four rings. The first three digits are valid numbers, the fourth digit is the multiplication number, and the fifth digit is the deviation. 5. Common Resistors 1. Potentiometer A potentiometer is an electromechanical component. It slides on the resistor body and obtains the output voltage related to the brush displacement. 1.1 carbon film potentiometer Synthesis The resistance body is coated with ground carbon black, graphite, Z and other materials on the substrate surface. This process is simple and is currently the most widely used potentiometer. It features high resolution, good wear resistance and long service life. The disadvantage is current noise, non-linearity, moisture resistance, and resistance stability. 1.2 Organic Solid Potentiometer Organic Solid potentiometer is a new type of potentiometer, which is a method of heating and plastic pressure, the organic resistance powder is pressed in the insulator groove. Compared with the carbon film potentiometer, the organic solid potentiometer has the advantages of good heat resistance, high power, high availability and good wear resistance. However, the temperature coefficient is large, the dynamic noise is large, the moisture resistance performance is poor, the manufacturing process is complex, and the resistance accuracy is poor. It is used for voltage and current adjustment in miniaturization, high availability, high wear resistance electronic equipment, AC and DC circuits. 1.3 metal glass uranium Potentiometer The metal glass uranium resistance slurry is coated on the ceramic matrix according to a certain figure by screen printing, which is formed by high temperature sintering. Features: wide resistance value range, good heat resistance, strong overload ability, moisture resistance, wear resistance, etc. are all very good, is a promising range of potentiometer, the disadvantage is the contact resistance and current noise. 1.4 winding Potentiometer The winding potentiometer uses the copper wire or nickel-chromium alloy wire as the resistance and wraps it around the insulation skeleton. The winding potentiometer is characterized by low contact resistance, high precision, and low temperature coefficient. Its disadvantage is poor resolution, low resistance, and poor high-frequency characteristics. It is mainly used for voltage divider, rheostat, zero-sum working points in the instrument, etc. 1.5 metal film Potentiometer The resistance body of the metal film Potentiometer can be composed of an alloy film, a metal oxide film, and a metal foil. It features high resolution, high temperature resistance, low temperature coefficient, low dynamic noise, and good smoothness. 1.6 conductive plastic Potentiometer The resistance slurry of DAP (phthalate didilute acrylic acid) is coated on the insulation body with special technology, and heated and aggregated into a resistance film, alternatively, the solid body formed by pressing the DAP resistance powder in the groove of the insulation matrix as the resistance body. Features: Good smoothness, excellent wear resistance, long service life, low dynamic noise, high availability, and chemical corrosion resistance. It is used in the Servo System of cosmic devices, missiles, aircraft radar antennas, etc. 1.7 potentiometer with switch Rotary toggle potentiometer, push/pull toggle potentiometer, and push/switch Potentiometer 1.8 preset Potentiometer Pre-adjusted Potentiometer in the circuit, once debugging is good, use wax sealing to adjust the position, generally do not adjust. 1.9 slip type Potentiometer Use the direct slide mode to change the resistance value. 1.10 dual-connected Potentiometer Has an exclusive-axis double-connected potentiometer and a coaxial double-connected Potentiometer 1.11 non-contact Potentiometer Non-contact potentiometer eliminates mechanical contact, long life, high availability, split-electric potentiometer, magnetic-sensitive potentiometer, etc. 2. Solid-core carbon Resistor A solid resistor is made of a mixture of carbon particles, conductive material, filler and adhesive. Features: The price is low, but the resistance deviation and noise voltage are both large, and the stability is poor. Currently, it is rarely used. 3. Winding Resistor It is made of high-Resistance Alloy Wire wound on the insulation skeleton, and heat-resistant glaze insulation or insulating paint is coated on the outside. The winding resistance has a low temperature coefficient, high resistance precision, good stability, heat resistance and corrosion resistance. It is mainly used for high-precision high-power resistance. The disadvantage is that the high-frequency performance is poor and the time constant is large. 4. Thin Film Resistors Evaporation is used to evaporate a certain resistivity material on the insulating material surface. The main features are as follows: 4.1 carbon film resistor The crystalline carbon is deposited on the skeleton of the ceramic rod. Low Cost, stable performance, wide resistance range, low temperature coefficient and low voltage coefficient of carbon film resistors are the most widely used resistors. 4.2 metal film resistor. Vacuum Evaporation is used to evaporate the alloy material on the surface of the Ceramic Rod skeleton. Compared with the carbon film resistance, the metal film resistance has higher precision, better stability, noise, and low temperature coefficient. It is widely used in instrumentation and communication equipment. 4.3 Metal Oxide Film Resistor A layer of metal oxides is deposited on the insulation rod. Because it is oxide, it is stable at high temperatures, heat-resisting impact, and strong load ability. 4.4 synthetic film Resistance The conductive compound suspension is coated on the substrate, so it is also called the paint film resistance. Because the conductive layer shows granular structure, its noise is high and its accuracy is low. It is mainly used to manufacture high voltage, high resistance and small resistor. 5. metal glass uranium Resistors The metal powder and glass uranium powder are mixed and printed on the substrate by screen printing. Wet resistance, high temperature, low temperature coefficient, mainly used in Thick Film circuits. 6. SMT The flake resistance is a form of metal glass uranium resistance. Its Resistance body is a high-availability RU series glass uranium material after high temperature sintering, the electrode uses silver palladium alloy slurry. Small size, high precision, good stability, because of its chip components, so high-frequency performance is good. 7. sensitive resistance Sensitive resistance refers to the temperature, voltage, humidity, light, gas, magnetic field, pressure and other sensitive resistors. The sensitive resistance symbol adds a diagonal line to the symbol of the common resistance and marks the type of the sensitive resistance, such as T. V. 7.1. Varistor Mainly silicon carbide and zinc oxide varistor, zinc oxide has more excellent characteristics. 7.2. Humidity Resistance Consists of wet layer, electrodes, and insulators. the wet-sensitive resistance mainly includes lithium chloride wet-sensitive resistance, carbon wet-sensitive resistance, and oxide wet-sensitive resistance. The wet-sensitive resistance of Lithium Chloride decreases with the increase of humidity. The disadvantage is that the test range is small, the characteristics are not reproducible, and the temperature is greatly affected. The disadvantage of carbon wet-sensitive resistance is low temperature sensitivity, and the resistance value is greatly affected by temperature. Due to aging characteristics, the temperature is rarely used. The wet-sensitive resistance of oxides has superior performance and can be used for a long time. The temperature has a small effect, and the changes in resistance and humidity are linearly related. It has tin oxide, nickel iron salt, and other materials. 7.3 photosensitive resistance Photosensitive resistance is an electronic component whose conductivity changes with the change of light transmittance. When a substance is under illumination, the concentration of the carrier increases, increasing the conductivity. This is the photoconductivity effect. 7.4. Gas Sensitivity Resistance Some semiconductors are made by oxidation and reduction reaction after absorbing a certain gas. They are mainly composed of metal oxides, including metal oxide gas sensitivity resistance, composite oxide gas sensitivity resistance, and ceramic Gas Sensitivity resistance. 7.5. Force-sensitive resistance The force-sensitive resistor is a type of resistance that changes with the pressure. It is called a piezoelectric resistor abroad. The so-called pressure resistance effect is the effect that the resistivity of semiconductor materials changes with the change of mechanical stress. It can be made into various torque meters, semiconductor microphones, pressure sensors, etc. The main varieties include silicon-sensitive resistors and selenium alloy force-sensitive resistors. Relatively speaking, the alloy resistors have higher sensitivity. Basic knowledge of circuit design (2) -- Capacitor Capacitor is one of the most widely used electronic components in electronic equipment. It is widely used in the fields of direct separation, coupling, bypass, filtering, tuning loop, energy conversion, and control circuit. The capacitance is expressed in C. The unit of capacitance is Farah (F), micro Farah (UF), pifarah (PF), 1f = 10 ^ 6 UF = 10 ^ 12pf. I. Method for naming capacitor Models The domestic capacitor model is generally composed of four parts (not suitable for varistor, variable, vacuum capacitor ). Name, material, category, and serial number are represented in sequence. Part 1: name, represented by letters, and C for capacitor. Part 2: material, represented by letters. Part 3: classification, which is generally represented by numbers and letters. Part 4: sequence number, represented by a number. Use letters to indicate the product materials: non-polar films such as a-ta electrolysis and B-polystyrene, C-high frequency ceramics, D-aluminum electrolysis, e-other materials electrolysis, G-alloy electrolysis, H-composite media, and I-glass Glaze polar Organic films such as J-metallic paper, L-polyester, N-Nb electrolytic, o-glass film, Q-paint film, T-low frequency ceramics, V-mother paper, Y-mica, z-paper Introduction 2. capacitor Classification Fixed capacitors, variable capacitors, and fine-tuning capacitors are divided into three categories by structure. Electrolyte: Organic Media capacitors, inorganic media capacitors, electrolytic capacitors, and air media capacitors. By application: high-frequency bypass, low-frequency bypass, filtering, tuning, high-frequency coupling, low-frequency coupling, small capacitor. High-frequency bypass: ceramic capacitor, Mica capacitor, glass film capacitor, polyester capacitor, glass glaze capacitor. Low-frequency bypass: Paper Capacitor, ceramic capacitor, aluminum electrolytic capacitor, polyester capacitor. Filter Wave: aluminum electrolytic capacitor, Paper Capacitor, composite paper capacitor, liquid ta capacitor. Harmonic adjustment: ceramic capacitor, Mica capacitor, glass film capacitor, polystyrene capacitor. High-frequency coupling: ceramic capacitor, Mica capacitor, polystyrene capacitor. Low-Frequency coupling: Paper Capacitor, ceramic capacitor, aluminum electrolytic capacitor, polyester capacitor, solid ta capacitor. Small capacitors: Metallic Paper Capacitor, ceramic capacitor, aluminum electrolytic capacitor, polystyrene capacitor, solid ta capacitor, glass glaze capacitor, metallic polyester capacitor, Polypropylene Capacitor, Mica capacitor. Iii. Common Capacitors 1. aluminum electrolysis capacitor A thin oxide film is used as a medium capacitor. because the oxide film has unidirectional conductive properties, the electrolytic capacitor has polarity. large capacity, high pulsation current capacity error, large leakage current; ordinary is not suitable for applications at high frequency and low temperature, it is not suitable to use low-frequency bypass, signal coupling, power filter at frequencies above 25 kHz 2. Ta Electrolytic Capacitor The sintered ta block is used as the positive electrode, and the temperature characteristics, frequency characteristics and properties of solid manganese dioxide used in electrolyte are superior to ordinary electrolytic capacitors, especially the leakage current is extremely small, the storage is good, and the service life is long, the capacity error is small, and the volume is small. The maximum capacitance and voltage product can be obtained per unit volume, which has poor resistance to the pulsating current. If the damage is easy to be in the short-circuit status, it is very high. 3. Film Capacitors The structure is similar to that of paper capacitors, but the low-loss plastic materials such as polyurethane and polystyrene have good dielectric frequency characteristics. The low dielectric loss cannot be large capacity, and the filters, integral, oscillating, and timing circuits with poor heat resistance can be used. 4. porcelain Capacitor A penetrating or column-type porcelain capacitor, one of its electrodes is the installation of screws. The lead inductance is very small, the frequency characteristic is good, the dielectric loss is small, there is a temperature compensation effect cannot be done into a large capacity, the vibration will cause the capacity change is particularly suitable for high-frequency Bypass 5. Dushi Capacitor (Multilayer Ceramic Capacitor) is coated with electrode Propeller Material on a number of Ceramic Film billet, and is folded together to form an integral whole, the small size, large capacity, high availability, and High Temperature Resistance capacitor is encapsulated by resin. The low frequency rock capacitor with high dielectric constant also has stable performance and is positive and small, q-value high-capacity error large noise bypass, filter, integral, oscillating circuit 6. Paper Capacitors Generally, two aluminum foil is used as the electrode with a thickness of 0.008 ~ in the middle ~ 012mm of capacitor paper is separated and wound together. The manufacturing process is simple, the price is low, and a large electrical capacity can be obtained. Generally, it is in a low-frequency circuit and generally cannot be greater than 3 ~ 4 MHz frequency. The pressure of the Oil-Immersed capacitor is higher than that of the ordinary paper capacitor, and the stability is good. It is suitable for high-voltage circuits. 7. fine-tuning Capacitors The electric capacity can be adjusted within a certain range, and can be fixed to a specific capacitance value after adjustment. The Q value and size of the porcelain dielectric capacitor are high and small. They can be divided into two types: tube and disc. 8. The mica and polystyrene media are usually spring-type east. The structure is simple, but the stability is poor. Wire-wound porcelain dielectric fine-tuning capacitor is the removal of copper wire <External electrode> to change the electrical capacity, so the capacity can only be smaller, not suitable for use in the case of repeated debugging 9. Ceramic Capacitors A capacitor ceramic with high dielectric constant named "Barium Titanate titanium titanate" is used as the medium to compress into a circular tube, a circular disc or a disc, and the silver plating on the ceramic is made as the electrode by burning the infiltration method. It is divided into two types: high-frequency porcelain and low-frequency porcelain. A capacitor with a small positive capacitance temperature coefficient is used in a high-stability oscillating loop as a loop capacitor and an integral capacitor. Low-frequency porcelain dielectric capacitors are used for bypassing or isolating DC in low-frequency circuits, or for scenarios with low stability and loss requirements, including high frequencies 〉. These capacitors are not suitable for use in pulse circuits because they are prone to pulse voltage breakdown. High frequency porcelain capacitor for high frequency circuit In terms of structure, Mica capacitors can be divided into foil and silver. The silver electrode is directly plated with silver layer by vacuum evaporation or burning infiltration. Due to the elimination of air gap, the temperature coefficient is greatly reduced, and the capacitor stability is also higher than that of the foil chip. High frequency, high Q value, and low temperature coefficient cannot be used as a large capacity. It is widely used in high-frequency electrical appliances and can be used as a standard capacitor. 10. The glass glaze capacitor is formed by spraying a special mixture suitable for spraying into a thin film, and the medium is then sintered with a silver electrode to form the "rock" structure performance comparable to that of the mica capacitor, it can withstand various climatic environments and generally works at 200 ℃ or higher temperatures. The rated operating voltage can reach 500 V, and the loss TG Delta 0. 0005 ~ 0.008 IV. Main characteristic parameters of capacitors: 1. Nominal capacity and allowable deviation The nominal electrical capacity indicates the electrical capacity on the capacitor. The difference between the actual capacity of the capacitor and the nominal capacity is called accurately within the permitted deviation range. Correspondence between precision level and allowable error: 00 (01)-± 1%, 0 (02) -± 2%, I-± 5%, ⅱ-± 10%, ⅲ-± 20%, IV-(+ 20%-10%), V-(+ 50%-20%), Vi-(+ 50%-30%) Generally, capacitor Levels I, II, and III are commonly used, and electrolytic capacitor levels IV, V, and VI are used. 2. Rated voltage The maximum DC voltage value that can be continuously added to the capacitor at the lowest ambient temperature and rated ambient temperature is generally directly indicated on the capacitor housing. If the operating voltage exceeds the voltage of the capacitor, the capacitor breaks down, this can cause irreparable permanent damage. 3. Insulation Resistance The ratio of DC voltage to capacitance is called insulation resistance. When the capacitance is small, it mainly depends on the surface state of the capacitor. When the capacity is greater than 0.1uf, it mainly depends on the performance of the medium. The smaller the insulation resistance, the better. The time constant of the capacitor: A Time Constant is introduced to properly evaluate the insulation of a large capacity capacitor, which is equal to the product of the insulation resistance and capacity of the capacitor. 4. Loss The energy consumed by capacitor heating per unit time under the action of an electric field is called loss. Each type of capacitor specifies its allowable loss value within a certain frequency range. The loss of the capacitor is mainly caused by the loss of the medium, the loss of the conductivity and the resistance of all the metal parts of the capacitor. Due to the DC electric field, capacitor losses exist in the form of leakage loss, which is generally small. Under the action of alternating electric field, capacitor losses are not only related to leakage loss, it is also related to the periodic polarization establishment process. 5. frequency features As the frequency increases, the electric capacity of a general capacitor decreases. V. capacitor capacity indication 1. Direct tagging Use numbers and Unit symbols. For example, 01uf indicates the 0.01 Micromethod, and some capacitors use "R" to indicate the decimal point. For example, R56 indicates the 0.56 micromethod. 2. Text notation Uses regular combinations of numbers and text symbols to represent the capacity. For example, P10 indicates 0.1pf, 1p0 indicates 1pf, 6p8 indicates 6.8pf, and 2u2 indicates 2.2 UF. 3. Color tagging The main parameters of the capacitor are represented by a color ring or a color point. The color method of the capacitor is the same as that of the resistor. Capacitor offset sign: + 100%-0--h, + 100%-10% -- R, + 50%-10% -- T, + 30%-10% -- Q, + 50%-20% -- S, + 80%-20% -- Z. Basic knowledge of circuit design (3)-inductor Coils The inductor coil is enclosed by wires in a circle * around the insulation tube, and the wires are insulated from each other. The insulation tube can be hollow or contain core or magnetic powder core (inductance. In l representation, the unit is Henry (H), Milli (MH), microhenry (Uh), 1 H = 10 ^ 3mh = 10 ^ 6uh. I. Classification of Inductance Classification by inductance: Fixed inductance and variable inductance. By the nature of the Guide magnet classification: Empty Core coil, ferrite coil, core coil, copper core coil. Classification by operating nature: Antenna coil, oscillating coil, throttling coil, trap coil, deflection coil. By Winding Structure classification: single-layer coil, multi-layer coil, honeycomb type coil. Ii. Main characteristic parameters of inductance coils 1. Inductive Volume l The inductance L represents the inherent characteristics of the coil and is irrelevant to the current size. Except for the special Inductance Coil (color-coded inductance), the inductance volume is generally not specifically labeled on the coil, but with a specific name. 2. Inductive strength XL The Inductance Coil blocks the AC current. The Inductance Coil is measured in ohm. The relationship between it and inductance L and AC frequency f is XL = 2 π fl 3. quality factor Q Quality factor Q is a physical quantity that represents the quality of the coil. Q is the ratio of the inductive resistance XL to its equivalent resistance, that is, q = XL/R The higher the Q value of the coil, the smaller the loss of the loop. The Q value of the coil is related to the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shield or the core, and the influence of the high-frequency skin effect. The coil's Q value is usually dozens to hundreds. 4. distributed capacitance The capacitance between the turns and turns of the coil, between the coil and the shield, and between the coil and the base is called the distribution capacitor. The existence of the distributed capacitor reduces the Q value of the coil and degrades the stability. Therefore, the smaller the distribution capacitor of the coil, the better. Iii. Common Coils 1. Single-layer Coil A single-layer coil is surrounded by insulated wires in a circle around the paper tube or plastic frame. Such as transistor radio medium wave antenna coil. 2. beehive Coils If the plane of the winding is not parallel to the rotating surface, it is intersecting into a certain angle. This coil is called a beehive coil. The number of times the wire is bent back and forth for one week, which is often referred to as the number of points. The advantage of the beehive bypass method is that the volume is small, the distribution capacity is small, and the electric sensing volume is large. The honeycomb coils are all made by means of the honeycomb winding machine. The larger the discount point, the smaller the distribution capacity. 3. Ferrite Core and Ferrite Core Coil The inductance of the coil is determined by whether there is a core. Inserting a Ferrite Core into an empty core coil increases the inductance and improves the coil quality. 4. Copper Core Coil The copper core coil is widely used in the ultra-short wave range. It uses the position of the rotating copper core in the coil to change the inductance. This adjustment is convenient and durable. 5. Color Code Inductor A color-coded inductor is an inductor with a fixed inductance. The inductance mark is marked by a color ring like a resistor. 6. Blocking Loop) The coil that limits the AC power to pass is called the resistance loop, which is divided into the high-frequency Resistance loop and the low-frequency Resistance loop. 7. deflection coil The deflection coil is the output-level load of the TV scanning circuit. The deflection coil requires high deflection sensitivity, uniform magnetic field, high Q value, small volume, and low price. Transformer Transformer is a device that changes the AC voltage, current, and impedance. When there is ac current in the primary coil, the core (or core) produces AC magnetic flux, generates voltage (or current) in the secondary coil ). A transformer is composed of an core (or core) and a coil. The coil has two or more windings. The winding connected to the power supply is called a primary coil, And the other winding is called a secondary coil. I. Classification By cooling type: dry (self-cooling) transformer, Oil Immersed (self-cooling) transformer, fluoride (evaporative cooling) transformer. Classified by moisture-proof type: Open transformer, filled transformer, and Sealed Transformer. Core or coil structures: Core Transformer (plug-in core, C-core, Ferrite Core), shell Transformer (plug-in core, C-core, Ferrite Core), ring transformer, metal foil transformer. Categories by Power Phase: Single-phase transformer, three-phase transformer, and multi-phase transformer. Categories by purpose: power transformers, voltage regulator transformers, audio transformers, medium frequency transformers, high-frequency transformers, pulse transformers. Ii. characteristic parameters of Power Transformers 1. operating frequency The Transformer Core Loss has a great relationship with the frequency. Therefore, it should be designed and used based on the frequency of use. This frequency is called the working frequency. 2 rated power The transformer can work for a long time at the specified frequency and voltage reduction, without exceeding the output power of the specified temperature rise. 3 rated voltage Refers to the voltage allowed to be applied on the transformer coil. The voltage shall not be greater than the specified value during operation. 4-byte Ratio The ratio of the primary voltage to the secondary voltage of the transformer. There is a difference between the no-load ratio and the load ratio. 5 no-load current When a transformer opens a circuit, there is still a certain amount of current in the initial stage. This part of current is called the no-load current. The no-load current is composed of the magnetization current (generating the magnetic flux) and the iron loss current (caused by the loss of the core. For 50Hz power transformers, the no-load current is basically equal to the magnetization current. 6 no-load loss: the power loss is measured at the initial stage when the transformer opens a circuit. The main loss is the loss of the core, followed by the loss (copper loss) of the no-load current on the copper resistance of the primary coil, which is very small. 7. Efficiency The percentage of the ratio of the secondary power P2 to the primary power P1. Generally, the higher the rated power of the transformer, the higher the efficiency. 8 insulation resistance It indicates the insulation performance between the transformer coils and between the coils and the core. The insulation resistance is related to the performance, temperature, and moisture of the insulation material used. Iii. characteristic parameters of audio transformer and high-frequency transformer 1. Frequency Response The characteristics of transformer output voltage that changes with the operating frequency. 2-pass band If the output voltage of the transformer at the intermediate frequency is U0, the frequency range when the output voltage (the input voltage remains unchanged) drops to 0.707u0 is called the transformer Band B. 3 initial and secondary impedance ratio The ratio of RO to Ri is called the ratio of primary and secondary impedance when the transformer is connected with the appropriate impedance Ro and ri at the beginning and the secondary impedance. In the case of impedance matching, the transformer works in the best state, with the highest transmission efficiency.