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60v too high

Discussion in 'General Electronics Discussion' started by polyal, Sep 8, 2011.

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  1. polyal

    polyal

    12
    0
    Sep 8, 2011
    i need to replace a 300w stereo power amp ( board ) with a 100w stereo power amp
    can i drop the 60-0-60v dc supply to 35-0-35v dc
    without replacing the transformer?
    regards
    polyal
     
  2. davenn

    davenn Moderator

    13,901
    1,971
    Sep 5, 2009
    hi polyal
    welcome :)

    Yes you could, but it would be some what involved.
    It would be far easier, quicker and probably cheaper to replace the transformer.

    cheers
    Dave
     
  3. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    This would be possible but would not be worthwhile and any fault in the control circuitry could finish the amp.
    If it is a transformer with visible laminations, it could perhaps, with dedication, be rewound with 60% of the original turns. If it is a toroidal transformer, this will be too difficult.
     
  4. polyal

    polyal

    12
    0
    Sep 8, 2011
    thanks for the replies

    is there a suitable way of splitting one 60v rail into 30-0-30 using a virtual earth
    thanks in advance
    polyal
     
  5. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    This is possible, you would need two equal resistors (1k?) in series with the centre connection going to a pair of npn transistors in darlington connection and also a pair of pnp transistors. The emitters should be connected together as the virtual earth. In theory, the net current should be zero so with fat capacitors on the output the power dissipated in the transistors should be low. The necessary size of the heat sinks would be determined by experience.
     
  6. polyal

    polyal

    12
    0
    Sep 8, 2011
    thanks for the relpy...is there anywhere i can see this config ( links etc )
    regards
    polyal
     
  7. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    This is the idea I had, perhaps others could comment.
     

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  8. polyal

    polyal

    12
    0
    Sep 8, 2011
    hi duke ...thanks for that..will investigate
    cheers
    polyal
     
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