Keywords: TDA2822M, active speaker
TDA2822M is a very classic excellent audio power amplification integrated circuit. In the early 1990s, it was widely used by domestic and foreign home appliance manufacturers in portable receptacles. Slightly powerful, especially with body speakers. TDA2822M can often be seen.
TDA2822M is a two-channel audio power integrated circuit developed for portable recording. It has the characteristics of low-level distortion and low static current, which can be operated in two-channel stereo or mono bridge amplification (BTL) mode. The TDA2822M operating voltage range is wide, and it works fine within 1.8V-15V.
The nominal output power of TDA2822M (1kHz, 8Ω, 9V, 10% total distortion) can reach 1W, and the bridge mode can reach 2W.
Other technical indicators of TDA2822M are as follows:
Maximum peak current (peakoutputcurrent): 1A;
QuiescentDraincurrent: ≤9mAVCC = 3V);
Total harmonic distortion (1kHz, 8Ω ~ 32Ω, typical value): 0.2%;
Closed loop gain (typ): 39dB;
Sound imbalance (stereo state, maximum): ± 1dB!
Sound separation (1kHz, stereo state, typical value): 50dB;
Input impedance (1kHz, minimum): 100kΩ;
Load range: ≥ 4Ω.
TDA2822M is cheap, but it is best to buy TDA at the beginning of purchase. It is best to use the semiconductor original, do not buy D start, do not buy TDA2822 (ie, no "m"). The former sound quality is not good, the latter has a narrow supply voltage range, there is a DIP16 package, which is relatively rare, and there is no comment.
In the actual production, there is a multi-bridge mode, and two output capacitors that are easily affected by the sound quality can be omitted. Figure 1 is a circuit diagram of a channel, which requires two sets of such circuits in actual production. The TDA2822M can work in a straight coupling method, provided that the input signal cannot with DC ingredient, otherwise the coupling capacitor should be added in the source input.
Do not pick up the speaker when power-on is first powered, and use the output terminal (between 1 foot and 3 feet). If you can use it at the millivolt level, otherwise it is best to pick up the input terminal (7 foot) Enter a 1UF high quality capacitor such as a CBB capacitor, of course, the electrolytic capacitance can also be. When measuring, you should pay attention to the gear of the multimeter, should be made up of the big move, don't put it on the minimum gear to avoid burnback.
The amplifier shown in Figure 1 is for the MP3 player, so the input resistance of the 7-pin is selected from 820 Ω, not typical 10kΩ, because the output load of the MP3 player is generally 32Ω headphones, although the electrical resistance of 32Ω may be compared Ok, but this MP3 player will compare power, and this amplifier is difficult to use other sound sources.
When actual production, you can use the experimental board directly, and the conditional adoption of the printed circuit board is better. When using a self-made printed circuit board, the components can be directly welded to the copper foil surface without drilling, and the components are directly soldered in the copper foil, that is, the so-called "root welding". The relocation element shorts the pin, and the TDA2822m is cut along the lower edge and welded.
If there is condition, the capacitance C2 of 5 pins in Figure 1 preferably uses a CBB capacitor to improve sound quality. In actual audition, you can remove the resistors R2, R3 and capacitance C4, C5 of 1, 3 feet. If the hearing is not different, the power amplifier is not self-excited, it is possible. The intuitive judgment method is: when self-excitement, IC temperature is greatly improved.
Since the TDA2822M is wide, the sound quality is very good, this amplifier can be used in computer multimedia amplifiers, and the listening is not less than one or two hundred yuan.
The entire circuit is powered by a separate transformer, and 6V ~ 9V can be used. Filtering and regulating can use common active filter circuits or three-terminal regulators to improve signal-to-noise ratio, here is recommended, as shown in Figure 2. The circuit is mainly different from the electrical filter circuit we generally found, and the inductance coil is added to the base of the triode, thereby achieving an ideal filtering effect using small power and small inductance. This circuit can be well filled with communication sound in the power supply.
The VT1 in Fig. 2 may also employ a medium power tube over 2A or more or more in 274, 2SD14092SD882. VT1, VT2 base capacitance C2, C3 uses an approximate capacity of CBB capacitance, and the effect is better. The inductance L1 can be self-made, and the enamel wire of the enameled line of φ0.15 mm can be used in 100 kΩ resistance. It can also be replaced by one winding in the middle of the radio, or the color code inductance of 330 mH can also be used.
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