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A way to boost a PSU output

Discussion in 'Hobby Electronics' started by Dave, Oct 13, 2004.

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  1. Dave

    Dave Guest

    G'day all, I have a small laptop PSU that I'm using for a portable HD
    based MP3 player.

    It can take an input voltage range of 10-18.7V DC and provide:

    +5V @ 4A
    +12V @ 0.7A
    -12V @ 0.1A
    -5V @ 0.05A

    It works fine from it's normal switchmode AC adapter, (17VDC @ 2.3A
    output), but powering it from the car cig. lighter, (12-14.4V), doesn't
    seem to provide enough 'oomph' to spinup the drive, (about 1.5A @ 12V).
    After it's spinning it only uses about 300mA @ 12V, 500mA @ 5V.

    I was just thinking of using a zener to provide an alternative 12V
    supply, using a power transistor to increase the current handling.

    Can't use a 7812 or similar because there's not enough voltage drop
    across it for it to work.

    I'd rather not go to the trouble of building another PSU, (ala the 12V
    ATX site).

    Anyone else got a 'simple' solution I could use?

  2. Spajky

    Spajky Guest
  3. Dave

    Dave Guest

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