Although inductors are less frequently used in electronic manufacturing than capacitors, they play an equally important role in circuit design. Inductors, as an energy storage component, can convert electrical energy into magnetic field energy and store this energy in the magnetic field. L is used to represent the inductor, and its basic unit is Henry (H), but because Henry is larger, millihenry (mH) is more commonly used in practical applications. Inductors usually work together with capacitors to form circuits such as LC filters and LC oscillators. In addition, the characteristics of inductors are also used to manufacture choke coils, transformers, relays and other equipment.
The characteristics of inductors are opposite to those of capacitors, i.e. they block the passage of alternating current and allow the passage of direct current. For example, an ordinary radio contains multiple inductor coils. These coils are usually made of enameled wire. They can be air-core coils or wound on a magnetic core or an iron core. These inductor coils include antenna coils, intermediate frequency transformers, input and output transformers, etc.
A transformer is a device composed of an iron core and copper coils wound around an insulating frame. Copper coils are wound on a plastic frame, and the coils are separated by insulating paper. After assembly is completed, multiple iron core sheets are inserted into the middle of the plastic skeleton, thereby significantly increasing the inductance of the coil. The transformer transmits electrical energy between its windings through the principle of electromagnetic induction. Its functions include coupling AC signals, blocking DC signals, and converting the input-output voltage ratio.
The main function of a power transformer is to convert high-voltage electricity into civil electricity. Many electrical equipment work with low-voltage DC power supply, which requires a power transformer to convert 220V AC mains power into low-voltage AC power, which is then rectified by diodes and filtered by capacitors to form DC power supply. For example, the high-voltage power supply for television picture tubes is provided by the line output transformer.
However, power transformers also have shortcomings such as large size and low efficiency, and are currently being gradually replaced by new electronic transformers. Electronic transformers usually refer to switching power supplies. For example, multiple sets of voltages required by computers are provided by switching power supplies. Switching power supplies are also commonly used in color TVs and monitors.
A relay is an electromechanical switch that consists of enameled copper wire wound on a round iron core. The number of coils can range from hundreds to thousands of turns. When electricity is passed through the coil, the magnetic field generated attracts the iron plates with contact blades on the core, thus switching the contacts. After the coil is powered off, due to the elasticity of the contact piece, the iron plate will leave the iron core and return to its original state. Relays can use very small currents to control the switches of other circuits. They are usually protected by plastic or plexiglass covers, and some are even fully sealed to prevent electric shock and oxidation.
To sum up, inductors are widely used in electronic circuits. They are not only used to form various filters and oscillators, but are also widely used in transformers, relays and other equipment. Through the correct use and application of inductors, the performance and reliability of electronic circuits can be significantly improved.