Monolayer coil A monolayer coil is an insulated wire wound round and round a paper tube or bakelframe. Such as the wave antenna coil in a transistor radio.

2. If the plane of the wound coil is not parallel to the rotating plane, but intersects at a certain Angle, the coil is called the honeycomb coil. The number of times the wire bends back and forth, often called the number of folds. The advantages of beehive winding method are small volume, small distributed capacitance and large inductance. Honeycomb coils are wound by honeycomb winding machine. The more folding points, the smaller the distributed capacitance.

3. The inductance of ferrite core and iron powder core coil is related to whether there is a magnetic core or not. Inserting ferrite core into hollow coil can increase inductance and improve coil quality. Copper coil Copper coil is widely used in the ultra-short wave range. The position of the copper core in the coil is used to change the inductance. This kind of adjustment is more convenient and durable.

5, color code inductor color code inductor is an inductor with a fixed amount of inductance, the method of marking the amount of inductance is the same as the resistance by color ring.

6. Choke coil (choke coil) The coil that restricts the flow of alternating current is called choke coil, which is divided into high-frequency choke coil and low-frequency choke coil.

Deflection coil Deflection coil is the load of the output stage of the TV scanning circuit. Requirements for deflection coil: high deflection sensitivity, uniform magnetic field, high Q value, small volume and low price. Transformer A transformer is a device that transforms ac voltage, current and impedance. When there is an AC current in the primary coil, ac flux will be generated in the iron core (or magnetic core), so that voltage (or current) will be induced in the secondary coil. A transformer consists of an iron core (or magnetic core) and a coil, which has two or more windings. The windings connected to the power supply are called primary windings and the remaining windings are called secondary windings.

Classification: dry-type (self-cooling) transformer, oil-immersed (self-cooling) transformer, fluoride (evaporative cooling) transformer. According to moisture-proof way classification: open transformer, sealed transformer, sealed transformer. Classification by core or coil structure: core transformer (insert core, C type core, ferrite core), shell transformer (insert core, C type core, ferrite core), ring type transformer, metal foil transformer. Classification by phase number of power supply: single-phase transformer, three-phase transformer, multiphase transformer. Classification by use: power transformer, voltage transformer, audio transformer, intermediate frequency transformer, high frequency transformer, pulse transformer.

The characteristic parameters of the power transformer

1, working frequency transformer core loss and frequency relationship is very big, so should be designed and used according to the use of frequency, this frequency is called the working frequency.

2. Rated power under the specified frequency and voltage, the transformer can work for a long time without exceeding the output power of the specified temperature rise.

3. Rated voltage refers to the voltage allowed to be applied on the coils of the transformer, which shall not be greater than the specified value during operation.

4. Voltage ratio refers to the ratio between the primary and secondary voltages of the transformer, with the difference between no-load voltage ratio and load voltage ratio.

5, no-load current transformer secondary open, the primary still has a certain current, this part of the current is called no-load current. The no-load current consists of magnetization current (which produces magnetic flux) and iron loss current (which is caused by core loss). For a 50Hz power transformer, the no-load current is basically equal to the magnetization current.

6. No-load loss refers to the power loss measured at the primary level when the transformer is secondary open. The main loss is the core loss, followed by the loss (copper loss) caused by no load current on the primary coil copper resistance, which is very small.

7. Efficiency refers to the ratio of secondary power P2 to primary power P1. Generally, the higher the rated power of the transformer, the higher the efficiency.

8. The insulation resistance represents the insulation performance between the coils of the transformer and between the coils and the iron core. The insulation resistance is related to the performance, temperature and humidity of the insulation material used.

Iii. Characteristic parameters of audio and high-frequency transformers

1. Frequency response refers to the variation of transformer secondary output voltage with operating frequency.

If the output voltage of the transformer at the intermediate frequency is U0, the frequency range when the output voltage (the input voltage remains unchanged) drops to 0.707U0 is called the transformer's passband B.

3. Primary and Secondary impedance ratio The primary and secondary impedance of the transformer are connected with appropriate impedance Ro and Ri to match the primary and secondary impedance of the transformer. Then the ratio of Ro and Ri is called the primary and secondary impedance ratio. In the case of impedance matching, the transformer works in the best state and has the highest transmission efficiency.