For engineers in the electronics industry, electronic components, like the rice that people eat, need to be touched and used every day. But in fact, many engineers may not fully understand the doorways inside. The following are ten electronic components commonly used by engineers and related basic concepts and knowledge. Let‘s learn together.

One: resistance

People say "resistors are the most used components in all electronic circuits." Resistors, because materials have a blocking effect on current flow, are called resistive materials in this role. Resistance causes changes in electron flux. The lower the resistance, the greater the flux of electrons and vice versa. Substances with no or very little resistance are called conductors, or conductors for short. Substances that cannot form current transmission are called electrical insulators, or insulators for short.

In physics, resistance is used to express the resistance of a conductor to current flow. The greater the resistance of the conductor, the greater the resistance of the conductor to current flow. The resistance of different conductors is usually different, and the resistance is a characteristic of the conductor itself. A resistance unit is an energy-consuming unit that hinders the movement of water.

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

Resistors are represented by "R" plus a number in the circuit. For example, R1 represents resistor number 1. The main functions of resistors in a circuit are shunt, current limit, voltage divider, offset, etc.

Two: Capacitor

Capacitance is the amount of charge stored at a given potential difference; the SI unit is Farah (F). In general, electric charges move under the action of force in an electric field. When there is a dielectric between conductors, it hinders the movement of charges and causes them to build up on the conductors; the most common example of charge accumulation storage is two parallel metal plates, also known as capacitors.

Capacitance is usually represented by a "C" plus a number in a circuit. A capacitor is an element consisting of two metal films in close proximity to each other, separated by an insulating material. The main feature of capacitors is their separation from DC and AC. Capacitor capacity is the amount of electrical energy that can be stored. The resistance of a capacitor to an AC signal is called capacitive reactance, which is related to the frequency and capacitance of the AC signal. Common types of capacitors used in telephones are electrolytic, ceramic, chip, monolithic, tantalum, and polyester.

Three: crystal diode

Semiconductor terminations in solid state electronic devices. The main feature of these devices is their nonlinear current-voltage characteristics. Since then, with the development of semiconductor materials and process technology, a variety of crystal diodes with diverse structures and different functional uses have been developed using different semiconductor materials, doping profiles and geometric structures. Materials of manufacture include germanium, silicon and compound semiconductors. Crystal diodes can be used to generate, control, receive, transform, amplify signals and perform energy conversion.

The main characteristic of the diode is unidirectional conduction, that is, the on-resistance is very small under the action of forward voltage, and the on-resistance is maximum or infinite under the action of reverse voltage. Due to the above characteristics, diodes are often used in circuits such as rectification, isolation, voltage regulation, polarity protection, coding control, frequency modulation and noise reduction of cordless phones. When measuring a diode with a digital multimeter, the red test lead connects to the positive electrode of the diode and the black test lead connects to the negative electrode of the diode, which is the positive on-resistance of the diode, which is the opposite of the connection method of the pointer multimeter.

Four: Zener diode

Zener diode, this diode is a semiconductor device with high resistance up to the critical reverse breakdown voltage.

The characteristic of the Zener diode is that after breakdown, the voltage across the Zener diode is basically unchanged. When a voltage regulator is connected to a circuit, if the voltage of the power supply fluctuates, or other reasons cause the voltage to change at various points in the circuit, the voltage across the load will remain essentially the same.

Five: Inductance

When a current is passed through the coil, a magnetic field is induced in the coil, and the induced magnetic field creates an induced current to resist the current passing through the coil. We call the interaction between the current and the coil the inductance, or inductance, in henries (h). It can also be used to make inductive components.

Inductance is often represented by "l" plus a number in a circuit. Induction coils are made by winding insulated wire around an insulating bobbin. DC can pass through the coil, and the DC resistance is the resistance of the wire itself, and the voltage drop is very small; when the AC signal passes through the coil, self-induced electromotive force will be generated at both ends of the coil. The direction of the self-induced electromotive force is opposite to that of the applied voltage, hindering the passage of the exchange. Therefore, inductance is characterized by DC resistance. The higher the frequency, the higher the coil impedance.

Six: varactor diode

Varactor diodes, also known as "variadic reactance diodes". It is a diode composed of a PN junction capacitor (barrier capacitor) and its reverse bias voltage Vr.

The varactor diode is a special kind of diode, which is designed according to the principle that the junction capacitance of the "PN junction" inside the ordinary diode changes with the change of the applied reverse voltage. The varactor diode is mainly used in the high-frequency modulation circuit of the mobile phone or the fixed phone in the cordless phone, and the low-frequency signal is modulated to the high-frequency signal for transmission. In the operating state, the varactor modulation voltage is usually applied to the negative electrode, so that the internal junction capacitance of the varactor varies with the modulation voltage. The failure of the varactor diode is mainly manifested as leakage or poor performance: (1) When leakage occurs, the high-frequency modulation circuit does not work or the modulation performance deteriorates. (2) When the performance of the varactor diode is deteriorated, the operation of the high-frequency modulation circuit is unstable, and the modulated high-frequency signal is sent to and received by the other party to generate distortion. When one of the above conditions occurs, the varactor of the same type should be replaced.

Seven: Transistor

Transistor is one of the basic components of semiconductor. It has the function of current amplification and is the core component of electronic circuits. A triode is fabricated on a semiconductor substrate by two PN junctions very close to each other. Two PN junctions divide the bulk semiconductor into three parts, the middle part is the base region, and the two sides are the emitter region and the collector region, arranged as PNP and NPN.

Transistors are often represented in circuits by "q" plus a number. A transistor is a special device that contains two PN junctions and has the ability to amplify.

Eight: Field Effect Tube

Field Effect Transistor is abbreviated as FET. Conductors are involved in majority conduction, also known as unipolar transistors. It belongs to a voltage-controlled semiconductor device. It has high input resistance (108~109Ω), low noise, low power consumption, large dynamic range, easy integration, no secondary breakdown, wide safe working area, etc. It has become a powerful bipolar transistor and power transistor. competitor.

FET has the advantages of high input impedance and low noise, and has been widely used in various electronic devices. Especially when the field effect transistor is used as the input stage of the whole electronic device, the performance that the general transistor can hardly achieve.

Field effect transistors are divided into two categories: junction type and insulating gate type, and their control principles are the same.

Nine. Sensors

A sensor is a physical device or biological organ that detects and senses external signals, physical conditions (such as light, heat, humidity) or chemical composition, and transmits the detected information to other devices or organs.

The definition of a sensor in the national standard gb 7665-87 is: "A device or device that can sense a specified measured component and convert it into a usable signal according to certain rules, usually consisting of a sensitive element and a conversion element". Meet the requirements of information transmission, processing, storage, display, recording and control. This is the first step in realizing automatic detection and automatic control.

In the new Welsh Dictionary, a "sensor" is defined as "a device that receives power from one system and sends power, usually in another form, to devices in a second system". According to this definition, the function of the sensor is to convert one kind of energy into another form of energy, so many scholars also call the sensor sensor.

Ten: Transformer

A transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are primary coil, secondary coil and iron core. In electrical equipment and wireless circuits, it is often used for voltage boosting, impedance matching and safety isolation.

In a generator, an electrical potential can be induced in the coil whether it is moved through a stationary coil by a magnetic field or by a magnetic field. In both cases, the value of the magnetic flux is constant, but the amount of magnetic flux that intersects the coil varies, which is the principle of mutual inductance. A transformer is a device that uses electromagnetic mutual inductance to convert voltage, current and impedance. The functions of the transformer mainly include: voltage conversion; current conversion, impedance conversion; isolation; voltage regulation.