resistance

As a worker in the electronics industry, resistance is well known. There is no doubt about its importance. It is said that "resistance is the most used component in all electronic circuits."

Resistance, because of the blocking effect of substance on current, it is called the resistive substance under this action. Resistance will lead to the change of electron flow. The smaller the resistance, the greater the electron flow, and vice versa. A substance with no or little resistance is called an electrical conductor, or conductor for short. Materials 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. The greater the resistance of the conductor, the greater the resistance of the conductor to the current. The resistance of different conductors is generally different. Resistance is a characteristic of the conductor itself. Resistance element is an energy dissipation element that hinders the current.

The resistance value of the resistance element is generally related to the temperature. The physical quantity that measures the resistance affected by the temperature is the temperature coefficient, which is defined as the percentage of the change of the resistance value when the temperature increases by 1 ℃.

The resistance is represented by "R" plus a number in the circuit. For example, R1 represents the resistance numbered 1. The main functions of resistance in the circuit are shunting, current limiting, voltage dividing, bias, etc.

capacitance

Capacitance (or capacitance) refers to the charge storage under a given potential difference; Marked as C, the international unit is farad (f). Generally speaking, the charge will move under force in the electric field. When there is a medium between the conductors, it hinders the charge movement and makes the charge accumulate on the conductor; The most common example of cumulative charge storage is two parallel metal plates. It is also commonly known as capacitor.

1. Capacitance is generally represented by "C" plus number in the circuit (for example, C13 represents the capacitance numbered 13). Capacitance is an element composed of two metal films close together and separated by insulating materials. The main characteristic of the capacitor is to isolate direct current and AC. The size of capacitance is the size of stored electric energy. The blocking effect of capacitance on AC signal is called capacitive reactance, which is related to the frequency and capacitance of AC signal. Capacitive reactance XC = 1 / 2 π FC (f represents the frequency of AC signal and C represents the capacitance capacity). The types of capacitors commonly used in telephone sets include electrolytic capacitor, ceramic chip capacitor, patch capacitor, monolithic capacitor, tantalum capacitor and polyester capacitor.

2. Identification method: the identification method of capacitance is basically the same as that of resistance, which can be divided into three methods: direct marking method, color marking method and number marking method. The basic unit of capacitance is expressed in farad (f), and other units include milli method (MF), micro method (UF), nano method (NF) and skin method (PF).

Crystal diode

Crystal diodes are semiconductor 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 technology, a variety of crystal diodes with various structures and functions have been developed by using different semiconductor materials, doping distribution and geometric structure. Manufacturing materials include germanium, silicon and compound semiconductors. Crystal diodes can be used to generate, control, receive, transform, amplify signals and convert energy.

Crystal diodes are often represented by "d" plus numbers in circuits. For example, D5 represents diodes numbered 5.

Zener diode

Zener diode (also known as zener diode), which is a semiconductor device with high resistance until the critical reverse breakdown voltage Zener diode is usually represented by "ZD" plus number in the circuit. For example, zd5 represents the zener tube numbered 5.

inductance

Inductance: when the coil passes through the current, a magnetic field induction is formed in the coil, and the induced magnetic field will generate induced current to resist the current passing through the coil. We call this interaction between current and coil electrical reactance, that is, inductance, and the unit is "Henry" (H). This property can also be used to make inductive elements.

Varactor diode

Varactor diodes are also known as "variable reactance diodes". It is a diode made by using the dependence and principle of PN junction capacitance (barrier capacitance) and its reverse bias voltage VR.

Crystal triode

Crystal triode is one of the basic components of semiconductor. It has the function of current amplification and is the core component of electronic circuit. Triode is to make two PN junctions close to each other on a semiconductor substrate. The two PN junctions divide the positive semiconductor into three parts. The middle part is the base area, and the two sides are the emission area and collector area. The arrangement modes are PNP and NPN.

Field effect transistor

Field effect transistor (FET) is abbreviated as field effect transistor. Most carriers participate in conduction, also known as unipolar transistor. It belongs to a voltage controlled semiconductor device. It has the advantages of high input resistance, low noise, low power consumption, large dynamic range, easy integration, no secondary breakdown phenomenon, wide safe working area and so on. It has become a strong competitor of bipolar transistor and power transistor.

transformer

Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. The main components are primary coil, secondary coil and iron core (magnetic core). In electrical equipment and wireless circuits, it is often used for voltage rise and fall, impedance matching, safety isolation, etc.