As player easy to carry, easy to operate, better sound quality and therefore were in favor of the school Philharmonic. However, players have adopted a low DC power supply (such as 1.5 V, 2V, 3V), the output power of small. I designed a special power output up to 1 W simple small amplifier, such as a loudness, noise reduction, volume and tone control, and other functions, and low cost, only 30 yuan. Its circuit schematics see at top.
Map, RL match for the resistance, and its value should be nominal load and players agreed to ensure that the player's output stage circuit work in the best working conditions. C3, C4, W2 and C1, C2, W1 are left and right channel and the volume control circuit, such as loudness, high-frequency noise and have a certain effect. R5 ~ R8, W5, W6, C9 ~ C12 and R1 ~ R4, W3, W4, C5 ~ C8 were a summary of the left and right channel tone control circuit. R13 ~ R16, C14 and R9 ~ R12, C13 respectively, a left and right channel noise reduction circuit and the simple low-pass filter, and the tone control circuit, and so clever with the TDA2822 can get the input of the record of similar signal Waveform, so that fidelity to improve. R18 and R20 output for the protection of resistance, because of output for the prevention of damage to short-circuit TDA2822. R22, LED1, LED2 composed of the circuit flow instructions, when the amplifier is greater than 400 mA operating current when, LED1 and LED2 will be luminous. C13 and C14 to enter straight at coupling capacitance, leakage should be the minimum quality of electrolytic capacitors, to facilitate smooth passage of audio signals, do not block signals. C17 and C18 to enter the playback of the access road, often in a typical circuit for 10 μ F or 47 μ F. Its input impedance is too large, would cause obstruction or signal from self-excited, here C17 and C18 will increase to 100 μ F, its quality has improved, the range broadens. C26 and C27 straight at the output coupling capacitance, usually choose to 220 μ F, this is too high output impedance, signal obstruction caused distortion, or even self-excited, C26 and C27 will now increase to 680 μ F, sound quality improved significantly, the range is wider.
The circuit as long as the correct installation, components of good quality and do not have to debug to work properly.
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