Ebays TDA2822M BTL to amplify guitar signal

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Bought this little amp from ebay and it works great amplifying my portable mp3 player.

(circuit diagram inside)


TDA2822M Amplifier Board DIY Parts | eBay

It's a variation of the circuit featured in the datasheet, as it includes C1, C2 and R1.

http://www.circuitdiagram.org/images...er-circuit.gif

What is the purpose of C1, C2 and R1, filtering?

How can I convert it to amplify my guitar's signal and use headphones as output? (maybe also use an fx pedal between the guitar and amp)

[PRR]

C1 C2 R1 cover all bases.

You can "probably" just put most signals right to pin 7.

However some signal sources have DC leak on their output, which would upset the TDA2822M. C1 blocks any external DC. Now the TDA2822M has no idea what DC to be, so R1 pulls it to a suitable DC level.

Meanwhile any long wire on the input will catch radio waves. We can't hear them directly, but strong radio may distort inside the TDA2822M and we hear voices, music, or garbled jibberish, not what we want. C2 diverts supersonics to ground.

TDA2822M has very high gain. You can feed guitar right in and get sound. But the impedance is low enough to suck the treble off the guitar. A buffer/booster in front may work better.

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Thank you for you help. If I understood correctly:

W1 and C2 form a low-pass filter, cutting all frequencies above the critical frequency defined by their values. W1=10k and C2=100pF; F=160Hz


C1 and R1 form a high-pass filter, cutting all frequencies bellow the critical frequency defined by their values. R1=10k and C2=4.7uF; F=3.4Hz

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Actually:

If the volume control is 10k and is set at half resistance then it has 5k from the signal source and has 5k to ground so as a part in a filter its resistance is 2.5k ohms.
With 100pF to ground its lowpass cutoff frequency is 640kHz to block AM radio stations and higher radio frequencies.
But a magnetic guitar pickup usually has a load of a few megohms so that it has a peak at its resonance of about 5kHz. the 10k volume control will cut its level a lot and cut its high frequencies a lot.

C1 has a source of 2.5k ohms from the volume control set at half resistance and a load of 10k for a total resistance of 12.5k ohms. With the 4.7uf coupling capacitor the highpass cutoff frequency is 2.7Hz so it will pass earthquake frequencies (from a geetar?). Maybe use a 0.33uF (330nF) film capacitor.