I have made an amplifier using TDA2002 but it's not working properly.
Pot. R1 is not included in mine as it doesn't make a lot of difference and produces noise when I try to adjust the volume.
How can this be solved?
Above a certain volume set in the music player, the 8 ohm, 3 inch diameter speaker gives out distorted sound.
How can I avoid this?
If the 3.5 mm jack isn't connected to an MP3 player or any audio device, there's a buzzing noise from the speaker.
How is this noise produced and how can it be removed?
A friend suggested that I add resistors in series to the input and the output. It din't work.
So he suggested that I add a buffer circuit to the input.
Will that help?
EDIT: I'm using a 5V, 0.7A supply.
Here's the circuit diagram
Best Answer
Distortion
Distortion can be caused (in this amp, assuming everyting is connected like it should be) by one of four causes:
Buzzing
The input picks up the electromagnetic field from the mains wires inside your house and amplifies them as if they were useful signal. To reduce the hum, you should put the amplifier in a metal case to shield it. It would still pick up some hum when the input is not connected to anything (or worse, connected to a wire which is not connected to anything), but that is not really important.
Also, the hum could be coming from the power supply (if you use a non-switching power supply) if there is insufficient filtering (not enough capacitors).
Resistor in series
It will not work - putting resistor in series with the input you will just lower the volume while putting the resistor in series with the speaker will reduce the output power because you will be wasting some power on the resistor. The amp will just start clipping at lower volume.
My suggestion
Find out the power of your speaker. Connect it to another (more powerful) amplifier and turn the volume up until you hear distortion. Note if the volume is flouder than with your amp or not. If it is the same, then you need a more powerful speaker.
If the chip can survive it (read the datasheet), use a higher voltage power supply, especially if you want to use an 8 ohm speaker. Or find a 4 ohm speaker - it would need less voltage for the same power (if your chip can drive 4 ohm speakers).