Hi guys,
I wanted to created a simple stereo system . So I bought a audio amplifier circuit from the local market which works really great. The only problem is the continuous buzzing sound . The noise is considerably loud . It raises as I increase the volume . But disappears as soon as I touch the heat sink of the amplifier . So I soldered all the metal body of bass, treble , volume potentiometers and even the heat sink to the negative terminal. This reduced the problem to a small extent .
I even tried soldering two 0.1micro farad capacitor with each channel (at audio input )with the negative of the audio jack but in vain .
My a amplifier is based on 4440 ic and has two sets of the same circuit on a single board for two channels . I have attached the image below .

I supplied it with 12v power from my bench power supply .
Plz help me solve this .
I wanted to created a simple stereo system . So I bought a audio amplifier circuit from the local market which works really great. The only problem is the continuous buzzing sound . The noise is considerably loud . It raises as I increase the volume . But disappears as soon as I touch the heat sink of the amplifier . So I soldered all the metal body of bass, treble , volume potentiometers and even the heat sink to the negative terminal. This reduced the problem to a small extent .
I even tried soldering two 0.1micro farad capacitor with each channel (at audio input )with the negative of the audio jack but in vain .
My a amplifier is based on 4440 ic and has two sets of the same circuit on a single board for two channels . I have attached the image below .


I supplied it with 12v power from my bench power supply .
Plz help me solve this .