1. Resistance
The blocking effect of a conductor on current is called the resistance of the conductor. Substances with low resistance are called electrical conductors, or conductors for short. Substances with high resistance are called electrical insulators, or insulators for short. In physics, resistance is used to express the resistance of conductors 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 property of the conductor itself.
The resistance of a conductor is usually represented by the letter R. the unit of resistance is Ohm, which is abbreviated as Ohm, and the symbol is Ω (Greek alphabet, transliterated into Pinyin) ō u mì g ǎ ）。 The larger units are kiloohms (K Ω) and megaohms (m Ω) (trillion = million, that is, 1million).
2. Capacitance
Capacitance (or electrical capacity) is a physical quantity that represents the ability of a capacitor to hold charge. The amount of electricity required to increase the potential difference between the two plates of a capacitor by 1 volt is called the capacitance of a capacitor. Physically speaking, a capacitor is a static charge storage medium (like a bucket, you can charge and store the charge. In the absence of a discharge circuit, the dielectric leakage is removed. The self discharge effect / electrolytic capacitor is obvious, and the charge may exist permanently, which is its feature). It has a wide range of uses. It is an indispensable electronic component in the field of electronics and power. It is mainly used in power filter, signal filter, signal coupling, resonance, DC isolation and other circuits. The symbol of capacitance is C.
C= ε S/4πkd=Q/U
In the international system of units, the unit of capacitance is farad, which is abbreviated as method, and the symbol is F. the commonly used units of capacitance are millifahrenheit (MF) and micro method（ μ F) , sodium method (NF) and skin method (PF) (skin method is also called Pico method), the conversion relationship is:
1 farad (f) = 1000 millimethod (MF) = 1000000 micro method（ μ F)
1 micro method（ μ F) = 1000 NF = 1000000 PF.
3. Inductance
Inductor is an element that can convert electrical energy into magnetic energy and store it. The structure of inductor is similar to that of transformer, but there is only one winding. The inductor has a certain inductance, which only prevents the change of current. If the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is connected; If the inductor is in a state of current flow, it will try to maintain the current when the circuit is disconnected. Inductor is also called choke, reactor and dynamic reactor.
4. Potentiometer
Potentiometer is a resistance element with three leads, and the resistance value can be adjusted according to a certain change law. Potentiometers usually consist of resistors and movable brushes. When the brush moves along the resistance body, the resistance value or voltage that is related to the displacement is obtained at the output end. The potentiometer can be used as either a three terminal element or a two terminal element. The latter can be regarded as a variable resistor.
Potentiometer is an adjustable electronic component. It is composed of a resistor and a rotating or sliding system. When a voltage is applied between the two fixed contacts of the resistance body, the position of the contact on the resistance body is changed by rotating or sliding system, and a voltage that is certain to the position of the moving contact can be obtained between the moving contact and the fixed contact. It is mostly used as a voltage divider. At this time, the potentiometer is a four terminal element. Potentiometers are basically sliding rheostats, which have several styles. They are generally used in the volume switch of speakers and the power adjustment of laser heads.
5. Transformer
Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Its main components are primary coil, secondary coil and iron core (magnetic core). The main functions are: voltage transformation, current transformation, impedance transformation, isolation, voltage stabilization (magnetic saturation transformer), etc.
Transformers are often used for voltage rise and fall, impedance matching, safety isolation, etc.
6. Diode
Diode is an electronic component with two electrodes, which only allows current to flow in a single direction. Many uses are based on its rectifier function. The varicap diode is used as an electronic adjustable capacitor
The current directivity of most diodes is usually called "rectifying". The most common function of diodes is to allow current to pass only in a single direction (called forward bias) and block it in the reverse direction (called reverse bias). Therefore, the diode can be thought of as an electronic check valve. However, in fact, diodes do not show such perfect on-off directivity, but rather more complex nonlinear electronic characteristics - which are determined by specific types of diode technology. The diode has many other functions besides being used as a switch
7. Triode
Triode, the full name of which should be semiconductor triode, also known as bipolar transistor, crystal triode, is a semiconductor device for current control. Its function is to amplify weak signals into electrical signals with large radiation value, and it is also used as a contactless switch. Crystal triode, one of the basic semiconductor components, has the function of current amplification and is the core component of electronic circuit. Triode is to make two closely spaced PN junctions on a semiconductor substrate. The two PN junctions divide the whole semiconductor into three parts. The middle part is the base area, and the two sides are the emission area and the collector area. The arrangement mode has PNP and NPN.
Triode is a kind of control element, which is mainly used to control the size of current. Taking the common emitter connection method as an example (the signal is input from the base, output from the collector, and the emitter is grounded), when the base voltage UB has a small change, the base current IB will also have a small change. Under the control of the base current IB, the collector current IC will have a big change. The larger the base current IB is, the larger the collector current IC is, and vice versa, The smaller the base current is, the smaller the collector current is, that is, the base current controls the change of collector current. But the change of collector current is much larger than that of base current, which is the amplification effect of triode.
8. MOS tube
MOS tubes are metal oxide semiconductor field effect transistors, or metal insulator semiconductors. The source and drain of MOS tubes can be switched. They are n-type regions formed in p-type backgate. In most cases, the two regions are the same, and even if the two ends are switched, the performance of the device will not be affected. Such devices are considered symmetrical.
The most remarkable characteristic of MOS transistor is its good switching characteristics, so it is widely used in circuits that need electronic switches, such as
Switching power supply and motor drive, as well as lighting dimming.
9. Integrated circuit
Integrated circuit is a kind of micro electronic device or component. Using a certain process, the transistors, diodes, resistors, capacitors, inductors and other components and wiring required in a circuit are interconnected, made on a small piece or several small pieces of semiconductor chips or dielectric substrates, and then packaged in a shell to become a micro structure with the required circuit functions; All the components have formed a whole in structure, making the electronic components a big step towards miniaturization, low power consumption, intelligence and high reliability. It is represented by the letter "IC" in the circuit.
The integrated circuit has the advantages of small size, light weight, less outgoing lines and welding points, long service life, high reliability, good performance and so on. At the same time, it has low cost and is convenient for mass production. It is not only widely used in industrial and civil electronic equipment such as tape recorders, televisions, computers and so on, but also widely used in military, communication, remote control and so on. The assembly density of electronic equipment assembled with integrated circuits can be dozens to thousands of times higher than that of transistors, and the stable working time of equipment can also be greatly improved