In this article today, we will introduce 9 simple audio amplifier circuit design schematic diagrams with a detailed explanation, complemented with some knowledge about amplifiers.
What is an audio amplifier?
An audio amplifier is a device that reconstructs an input audio signal on an output element that produces sound. The reconstructed signal volume and power level are ideal. They are truthful, effective, and low distortion. The audio range is from 20Hz to 20 kHz, so the amplifier must have a good frequency response within this range. Depending on the application, the power varies greatly. From milliwatts of headphones to several watts of TV or PC audio, to dozens of watts of mini home stereo and car audio, to hundreds of watts or more of more powerful household and commercial audio systems, until the power is big enough to meet the sound requirements of an entire cinema or auditorium.
The development of audio amplifiers has gone through three times. They are electron tube (vacuum tube) time, bipolar transistor time, and field-effect transistor time. The electronic tube audio amplifier has a round and sweet timbre, but it has the disadvantages of large volume, high power consumption, unstable operation, and poor high-frequency response. For the bipolar transistor audio amplifier, it has the advantages of a wide frequency band, large dynamic range, high reliability, long life, and high-frequency response is good. However, its static power consumption and on-resistance are very large, and the efficiency is difficult to improve. The third one is the field-effect transistor audio amplifier. It has the same round and sweet timbre as the electron tube and its dynamic range is wide. More importantly, it has a small on-resistance and can achieve high efficiency.
Next, I would like to introduce nine simple audio amplifier circuit design schematic diagrams.
Circuit Diagram 1This circuit makes full use of the conventional LM317 voltage adjustment chip so that it not only completes the voltage stabilization function of the unstabilized voltage after filtering but also realizes the function of amplifying the audio signal picked up by the electret capacitive microphone. The electret capacitive microphone contains an impedance converter based on JFET, which converts the speech signal into a current form and adds it to the RP resistor, causing the corresponding voltage change. 220V AC output 36V unstable DC through transformer and bridge rectifier, and after filtering by the capacitor, the low resistance audio amplification signal input by the LM317 on the DC is fed into the capacitor and output to the loudspeaker. The implementation circuit is shown in figure 2.
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