Frequency response of audio transformer and high frequency transformer
Frequency response of audio transformer and high frequency transformer
(1) the output voltage of the two side of the transformer varies with the operating frequency.
(2) When the intermediate frequency output voltage of the transformer is U, when the output voltage (input voltage remains unchanged) drops to 0.707U, the frequency range is called the transformer passband B.
(3) the first and the first impedance are the proper impedance of the first and the second sides of the transformer. And R, to match the first and second impedance of the transformer, then R and R; the ratio is called the first and second impedance ratio. In the case of impedance matching, the transformer works best and has the highest transmission efficiency.
(4) in addition to the audio transformer, the rated power is directly digitally expressed, VA.
(5) serial numbers are represented by numbers. Note: transformer type does not contain intermediate frequency transformer, line output transformer and other special transformers.
The parameter identification of transformer is usually expressed by the direct method of transformer. The specific content of transformer for various purposes is different. The label of an audio output transformer of the second coil pin is 8 ohm, indicating that the transformer of the secondary coil is negative and the load impedance should be 8OHM. It can only load 8 ohm. Impedance connection.
DB 50-2 is marked on the power transformer, where DB represents the power transformer; 50 represents the rated power of 50V. A; 2 indicates the serial number of the product.
Some power transformers label transformer circuit symbols (the structure of each coil) on the housing, and then label voltage values on each coil symbol to explain the output voltage of each coil.
Common transformers
1. Low-frequency transformer can be divided into audio transformer and power transformer, in the circuit can be divided into transformer, output transformer, stage coupling transformer, push-pull transformer and line transformer. This transformer is an iron core transformer whose structure is mainly a E core or core.
2. The main function of audio amplifier in amplifier circuit is coupling, inverting, impedance matching and so on. Audio frequency transformer is required to have good frequency characteristics, small leakage inductance and small distributed capacitance. A transformer is an audio transformer connected to the transmission end of an amplifier. The primary side of the transformer is connected to a cable or a microphone, and the secondary side is connected to the first stage of the amplifier. However, the coupling transformer between the transistor amplifier's low amplifier and the power amplifier is also called the transmission transformer, the former is called the transmission transformer and the voice simple transformer respectively.
Transformer cores are usually made of high permeability ferrite or permalloy, while low grade cores are usually made of high quality silicon steel. The secondary side of the transformer is usually provided with three lead-out terminals to provide symmetrical driving signals with the opposite phase to the push-pull output stage of the transistor power amplifier.
The output transformer is a transformer connected to the output of the amplifier. Its primary side is connected to the output of the amplifier, and its secondary side is connected to the load (loudspeaker, etc.). Its main function is to reduce the impedance of loudspeaker, and change the load impedance into the optimum load impedance of amplifier by output transformer, so that the amplifier has the maximum distortion and achieves the purpose of output impedance matching. The output transformer also has the function of isolation amplifier and load DC circuit. According to the output power level of the circuit, the output transformer has two sides: one side and push pull. The nominal power of the output transformer is generally greater than the nominal power of the transformer, and the shape structure and circuit symbols are similar to the transformer.