What is the function of the audio transformer?
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Update time : 2022-08-30 17:04:53
Transformer functionTransformer is a device that uses the principle of electromagnetic induction to change the AC voltage.The main components are the primary coil, the secondary coil and the iron core (magnetic core). The main functions are: voltage transformation, current transformation, impedance transformation, isolation, voltage regulation (magnetic saturation transformer), etc. According to the purpose, it can be divided into: power transformers and special transformers (electric furnace transformers, rectifier transformers, power frequency test transformers, voltage regulators, mining transformers, audio transformers, intermediate frequency transformers, high frequency transformers, impact transformers, instrument transformers, electronic transformers , reactors, transformers, etc.). Circuit symbols often use T as the beginning of the number. Example: T01, T201, etc.
The role of audio transformers1. The power transformer, the general audio uses DC power. For example, the ordinary socket in some countries is AC 220V, so it needs to be stepped down and rectified to supply the audio. If the 220v power is used directly, the audio components will be damaged.
2. Impedance transformers are used for some constant voltage power amplifiers to connect speakers, and do a matching role between the power amplifier and the speakers.
3. In addition, the audio transformer is different in that it has a feedback winding, which provides a positive feedback signal to the PWMIC to generate high-frequency oscillation together with the primary winding, so that the DC entering the primary winding of the transformer has a large AC Element. After the high-frequency AC component is isolated by the magnetic core of the transformer, a pure high-frequency alternating current is formed in the secondary, which is rectified and filtered to supply the electrical equipment.
4. The audio power amplifier transformer often encounters a current sound or a "hum" sound during operation. Insufficient power will cause a current sound. The toroidal transformer winding evenly and tightly wraps the toroidal core, effectively reducing the "hum" sound caused by magnetostriction. The toroidal transformer can be overloaded instantaneously and can accept the impact of large current caused by the bass.
D2-3500 internal structure diagram (including transformer)
Why use a toroidal transformer for audio1. The reason for the obvious current noise is that the power of the power supply is too small, the second is that the filter capacitor capacity of the power supply is insufficient, and the third is that the switching power supply is a non-linear power supply, and if the circuit is not handled well, an induced current will be formed;
2. The use of toroidal transformers for speakers is determined by the characteristics of audio amplifiers. It is not necessary to use a toroidal transformer for speakers, but it is most suitable to use a toroidal transformer.
Unlike other equipment, the power consumption of electrical equipment is basically fixed. The power consumption of audio power amplifiers not only changes rapidly, but also changes by 10,000%; such a large change requires that the transformer must have a strong instantaneous overload capacity and a fast response speed. Otherwise, it will easily form noise, the sound is not full, and the sound quality is not good. Due to the large capacity of the toroidal transformer in the same volume, the direct-coupled type has almost zero delay response, which meets the characteristics of the speaker supply point;
3. Characteristics of toroidal transformers
The core of the toroidal transformer is made of high-quality cold-rolled silicon steel sheets (generally below 0.35mm in thickness), which are seamlessly rolled, which makes its core performance better than the traditional laminated core. The coil of the toroidal transformer is evenly wound on the iron core, and the direction of the magnetic field lines generated by the coil almost completely coincides with the magnetic circuit of the iron core. Compared with the laminated type, the excitation energy and core loss will be reduced by 25%, which brings a series of advantages as described below.
1) The high-efficiency iron core has no air gap, and the lamination factor can be as high as 95%.
2) Small size. Light weight toroidal transformers can be half the weight of laminated transformers.
3) The magnetic interference is small. The toroidal transformer core has no air gap, and the windings are evenly wound on the toroidal core. This structure leads to small magnetic flux leakage and small electromagnetic radiation. High-sensitivity electronic equipment can be used without additional shielding. , such as low-level amplifiers and medical equipment.
4) Less vibration and noise. There is no air gap in the iron core, which can reduce the noise of the induced vibration of the iron core, and the windings evenly and tightly wrap the annular iron core, effectively reducing the "hum" sound caused by magnetostriction.
5)The operating temperature rise is low. Since the iron loss can be 1.1W/kg, the iron loss is very small, the temperature rise of the iron core is low, and the winding is well dissipated on the iron core with a lower temperature, so the temperature rise of the transformer is low.
6) Easy to install. The toroidal transformer has only one mounting screw in the center, which is particularly easy to quickly install and remove in electronic equipment.
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