Top ten most commonly used electronic components (I)

resistance:

As a worker in the electronics industry, the resistance is unintelligible. Its importance is beyond doubt. People say "resistance is the most used component in all electronic circuits."

Resistance, because the substance hinders the current, so it is called the resistance material under the action. The resistance will cause a change in the amount of electron flow. The smaller the resistance, the larger the electron flux and vice versa. A substance without resistance or resistance is called an electrical conductor, or a conductor for short. A substance that cannot form a current transmission is called an electrical insulator, or simply an insulator.

In physics, resistance is used to indicate the magnitude of the conductor's resistance to current. The greater the resistance of the conductor, the greater the resistance of the conductor to the current. Different conductors have different resistances, and resistance is a characteristic of the conductor itself. The resistive element is an energy consuming element that blocks the current.

The resistance value of the resistance element is generally related to temperature. The physical quantity that measures the magnitude of the resistance of the resistance is the temperature coefficient, which is defined as the percentage change of the resistance value for every 1 °C increase in temperature.

The resistor is represented by a "R" plus a number in the circuit. For example, R1 represents a resistor numbered 1. The main role of the resistor in the circuit is shunt, current limit, voltage division, offset, and so on.

Parameter identification: The unit of resistance is ohm (Ω), and the unit of magnification is: kilo ohm (KΩ), megohm (MΩ) and so on. The conversion method is: 1 megaohm = 1000 kohm = 1000000 ohm resistance There are three kinds of parameter labeling methods, namely, the direct label method, the color scale method and the number standard method. a, the number standard method is mainly used for small-volume circuits such as patches, such as: 472 means 47 × 100 Ω (that is, 4.7K); 104 means 100Kb, color ring labeling method is the most used, the current example is as follows: four color ring resistance five colors Ring resistance (precision resistance).

The relationship between the color mark position and the magnification of the resistor is shown in the following table: Color Effective Digital Magnification 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 gray 8x100000000/white 9x1000000000/.

capacitance:

Capacitance (or capacitance) refers to the amount of charge stored at a given potential difference; denoted as C, the international unit is Farad (F). In general, charges are forced to move in an electric field. When there is a medium between the conductors, the charge is prevented from moving and the charges are accumulated on the conductor; the cumulative storage of charges, the most common example is two parallel metals. board. It is also a common name for capacitors.

The capacitor is generally represented by a "C" plus a number in the circuit (for example, C13 represents a capacitor numbered 13). The capacitor is an element consisting of two metal films abutting and separated by an insulating material. The characteristics of the capacitor are mainly DC-blocking AC. The size of the capacitor capacity is the size of the energy that can be stored. The blocking effect of the capacitor on the AC signal is called capacitive reactance, which is related to the frequency and capacitance of the AC signal. Capacitive reactance XC=1/2πfc (f indicates the frequency of the AC signal, C indicates the capacity of the capacitor) The types of capacitors commonly used in telephones are electrolytic capacitors, ceramic capacitors, chip capacitors, monolithic capacitors, tantalum capacitors, and polyester capacitors. Please visit: Transmission and Distribution Equipment Network for more information.

Identification method: The identification method of the capacitance is basically the same as the identification method of the resistance, and there are three types: the direct label method, the color scale method and the number standard method. The basic unit of the capacitance is pulled (F), and other units are: millifarad (mF), microfarad (uF), nanofarad (nF), and picofarad (pF). Among them: 1 Farad = 10^3 millifarad = 10^6 microfarad = 10^9 nanofarad = 10^12 picofarad, the capacity of the capacitor is directly indicated on the capacitor, such as 10uF/16V capacitor The capacity value is represented by letters or numerals on the capacitor. The letter representation: 1m=1000uF1P2=1.2PF1n=1000PF Digital representation: Generally, the three-digit number is used to indicate the capacity. The first two digits represent the effective digits, and the third digit is the magnification. . Such as: 102 means 10 × 102PF = 1000PF224 means 22 × 104PF = 0.22uF3, capacitance capacity error table symbol FGJKLM allowable error ± 1% ± 2% ± 5% ± 10% ± 15% ± 20% such as: a ceramic capacitor is 104J indicates a capacity of 0.1 uF and an error of ±5%.

Crystal diode:

Semiconductor two-terminal devices in crystaldiodes. The main feature of these devices is their non-linear current-voltage characteristics. Since then, with the development of semiconductor materials and process technology, a variety of crystal diodes with various structures and different functional uses have been developed using different semiconductor materials, doping profiles, and geometric structures. The materials used are germanium, silicon and compound semiconductors. Crystal diodes can be used to generate, control, receive, transform, amplify signals, and perform energy conversion.

The crystal diode is usually represented by a "D" plus a number in the circuit, such as: D5 represents a diode numbered 5.

Function: The main characteristic of the diode is unidirectional conductivity, that is, the on-resistance is small under the action of the forward voltage; and the on-resistance is extremely large or infinite under the action of the reverse voltage. Because diodes have the above characteristics, they are often used in cordless telephones in circuits such as rectification, isolation, voltage regulation, polarity protection, code control, frequency modulation, and squelch. The crystal diodes used in the telephone can be divided into rectifier diodes (such as 1N4004), isolation diodes (such as 1N4148), Schottky diodes (such as BAT85), light-emitting diodes, and Zener diodes.

Identification method: The identification of the diode is very simple. The N pole (negative pole) of the small power diode is mostly marked with a color circle on the outer surface of the diode. Some diodes also use the diode-specific symbol to indicate the P pole (positive pole) or the N pole (negative pole). ), there are also signs using the symbol "P", "N" to determine the polarity of the diode. The positive and negative poles of the LED can be identified by the length of the pin, the long leg is positive and the short leg is negative.

Test Note: When using a digital multimeter to measure the diode, the red test lead is connected to the positive pole of the diode, and the black test lead is connected to the negative pole of the diode. The measured resistance value is the forward conduction resistance value of the diode, which is compared with the pointer type multimeter. The test leads are just the opposite.

The commonly used 1N4000 series diode withstand voltage is compared as follows: Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007 withstand voltage (V) 50 100 200 400 600 800 1000 current (A) are 1.