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Examination Of Audio Transformer

Transformers are a part of electronic equipments and form an important part of our daily life. Audio transformers play an important part of any audio equipment. They differ from Power transformers. They give matching electrical characteristics of an output amplifier to any loud speaker. They are used for voice communication only. They operate from 200 Hz to 500 Hz. In High fidelity audio equipments audio transformers can operate from 20 Hz to 20 KHz. Thus they determine the quality of the sound produced from an audio output. Designing the electronic circuits which give low distortion of sou nd levels is easy to design.

Audio transformers have different rated DC current. They also have output power and operating frequency range. The insertion loss is also varied. The measured loss is the loss through a device that excludes the power division factor and is the ratio of the power input to the power output. The 3-decibel bandwidth or the 3-dB bandwidth is also varied. This is the frequency range over which the insertion loss is less than 3-dB for mid band insertion loss. The direct current resistance or DCR is also varied. This is the resistance of the winding current that is measured in DC current. In the design of audio transformers this is often minimized and it is specified as maximum rating.

The main object of audio transformers is to make the quality of sound better by reducing the interference of audio signals. There is an interference of a buzzing or a humming background sound that is heard when other electronic devices are used. This is due to the voltage from other electronic equipments. In audio equipments, the audio transformer is generally built in and encased in a magnetic shielding. This shielding provides the insulation. This is filled with epoxy resin. This shielding also gives protection to the windings and helps in stopping the vibration of the core material.

Audio transformers vary in the certain aspects. Some of them do not have a center tap. Some have it only in the primary side while some have it in the secondary side. Still others have it both the primary and the secondary sides. In audio transformers it is necessary to see that the impedance ratio is equal to that of the square-of-the-turn ratio.

In an audio transformer when there is good low frequency, a large iron core is necessary. With higher power, the core size needs to become increased. The main thing to take note of is that the windings should be designed with care, without too much leakage inductance and stray capacitance. This will give the best high frequency response.

The audio transformer is very useful. It is used to couple stages of amplifiers. It is used also in microphones and record playing cartridges. Here it matches the equipment with the input impedance of the amplifier. In telephones, the circuits of the audio transformers allow a two way conversation on a single pair of wires. It is used for isolation in external cables and internal circuits. Audio transformers also help to couple differential-mode signal to a ground-referenced signal.

Audio transformers have thus made sound that is produced by audio equipments clear, without any impedance. Cutting off the background noise and the other vibrations from voltage fluctuations makes listening to good audio music a pleasure indeed. Improvements in audio transformers have indeed made the quality of sound better.