Applications and characteristics of inductors

Although inductors are not used much in electronic production, they are equally important in circuits. We believe that inductors, like capacitors, are also energy storage components that can convert electrical energy into magnetic field energy and store energy in the magnetic field. Inductors are represented by the symbol L, and their basic unit is Henry (H), and millihenry (mH) is often used as the unit. They often work with capacitors to form LC filters, LC oscillators, etc. In addition, people also use the characteristics of inductance to manufacture chokes, transformers, relays, etc.

The characteristics of an inductor are exactly opposite to those of a capacitor. It has the characteristics of blocking AC current from passing through but allowing DC current to pass through.
There are many inductor coils on a small radio, almost all of which are hollow coils wound with enameled wire or wound on a skeleton magnetic core or iron core. There are antenna coils (which are made of enameled wire wound on a magnetic rod), intermediate frequency transformers (commonly known as intermediate frequency transformers), input and output transformers, etc.

The transformer is composed of an iron core and a copper coil wire wound on an insulating frame. The insulated copper wire is wound on a plastic frame, and each frame needs to be wound with two sets of input and output coils. The middle of the coil is isolated with insulating paper. After winding, many iron core sheets are inserted in the middle of the plastic frame. In this way, the inductance of the coil can be significantly increased. The transformer uses the principle of electromagnetic induction to transmit electrical energy from one winding to another. The transformer has important functions in the circuit: coupling AC signals and blocking DC signals, and can change the input and output voltage ratio; using the transformer to make the impedance at both ends of the circuit well matched to obtain the maximum transmission signal power.
The power transformer is to convert high voltage electricity into civil mains electricity, and many of our electrical appliances work with low-voltage DC power supply. A power transformer is needed to convert 220V AC mains electricity into low-voltage AC power, and then through diode rectification and capacitor filtering, a DC power supply is formed to work. The TV picture tube requires a voltage of tens of thousands of volts to work, which is supplied by the "line output transformer".

Of course, power transformers also have many disadvantages, such as power is proportional to volume, bulky, low efficiency, etc. Now they are being replaced by new "electronic transformers". Electronic transformers are generally "switching power supplies". The several sets of voltages required for computer operation are supplied by switching power supplies. Color TVs and monitors all use switching power supplies without exception.