Tda 7297 amp has noise and touching heat sink.

Discussion in 'General Electronics Chat' started by Htin Aung, Jun 17, 2016.

  1. Htin Aung

    Thread Starter New Member

    May 29, 2016
    21
    0
    Hello everybody, I created my own amp with TDA 7297 IC.
    Now I had a problem. It has some noice.when i touch the heat sink, the noice has decrease.
    I don´t think or prefer to repair it less of noice , coz it is an amp.
    But I still wanna decreases the noice without touching the heat sink.I tried to ground it, but it has no change.
    But When i touch heat sink, noice has decreased.
    Please help me. :-D amplifier_circuit_tda7297_schematic.png
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,968
    387
    Is the noise hiss or hum (high or low frequency)?
    Are you using a switch-mode power supply?
     
  3. Htin Aung

    Thread Starter New Member

    May 29, 2016
    21
    0
    No I didn´t use any power supply.
    I used only 12V 1A Adaptor for power supply.
    There is no switch sir.
     
  4. Picbuster

    Member

    Dec 2, 2013
    376
    50
    Did you follow pcb layout advice s described in datasheet?
    I smell oscillation.
    Is your pwrsupp able to deliver 2 x15W + overhead caused by the circuitry?
    Please connect a scope and observe the output.
    Picbuster
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,809
    1,105
    Is the noise present when you have a signal source properly connected to the input, or only when the input is floating (open circuit)?
    What is your signal source?
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,001
    745
    What's it like when you power it from a 12v battery?
     
  7. Htin Aung

    Thread Starter New Member

    May 29, 2016
    21
    0
    Both condition sir.
     
  8. Htin Aung

    Thread Starter New Member

    May 29, 2016
    21
    0
    No I didn´t try this way.
    I´ll have to try so..
    Thanks
     
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