Why is my audio amplifier oscillating?

Question

I'm trying to make a small audio amplifier using a TDA2822 stereo amplifier. It is working as expected, but it has some noise that will make you not hear the audio when I increase the volume on my phone connected to it through the earphone jack.

Why is it oscillating the noise when I increase the audio volume to about 30 percent upwards but I can hear it clearly when the volume is below 30?

Here is my circuit:

I tried adding a pull-down resistor to both input and output and it is still the same. I tried reducing the output capacitor value, but still get the same results.

Advise needed on how to get rid of the high output noise.

Answer 1

What you have designed isn't what is shown in the data sheet. They typically show a connection (two channel) like this: -

• You have used a capacitor on the non-inverting input when it needs a pull-down resistor
• You have used a pull-down resistor on the inverting input when it needs a capacitor.
• The data sheet also shows a Zobel network on the output, yours has none
• You have used a 1 μF supply decoupler whereas the data sheet shows a 10 μF

These are all significant differences but, you could have made other notable "audio-amplifier" errors in how you wired your power source to the IC.