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What does a buffer do? In the given circuit,it is said that capacitors C1 and C4 act as buffer .What is their role here?Can't we just replace them with pull-down resisrors? Speaker Circuit

  • I would call C1 and C4 power supply filter capacitors (or bypass capacitors). I don't think I've heard the term "buffer capacitor" for that use. – Peter Bennett Oct 22 '14 at 05:45

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For reference the TDA2822M datasheet can be found here.

Those capacitors are connected to the power supply pin (pin #2). They are acting as bypass capacitors. Bypass capacitors are designed to remove AC noise from the DC supply voltage. Since capacitors are a short at high frequencies, high frequency noise is shorted to ground while the DC supply voltage is passed.

You would not want to replace them with pull-down resistors. You don't want to pull down the supply voltage, and if you replaced them high frequency noise would be passed to the supply pin of the IC.

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  • OK.Does resistance cause any disturbances in dc supply?I know that switch causes due to debouncing so capacitor is placed sfter it.If the capacitor C1 is placed parallel to the power source instead of the present position,then it may filter the supply even earlier. –  Oct 22 '14 at 05:37