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power suppy step down

Discussion in 'General Electronics Discussion' started by paul60, Dec 11, 2010.

  1. paul60

    paul60

    22
    0
    Dec 11, 2010
    I have a power suppy input 120v 0.22a 26va
    output 30v 400ma 12va
    using my multimeter i get a reading of 37 volts
    what i am trying to do is to reduce the voltage to 24 volts.
    can anyone tell me how to go about this.
    or where i can find a circuit diagram.
    thanks paul
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,178
    2,690
    Jan 21, 2010
    You need a voltage regulator. If you get a 3 terminal regulator (the simplest to use) then you'll want one that allows an input voltage between 40 and 45 volts (to give some safety margin),

    You also might need some more filter capacitors if the existing power supply has insufficient. 470uF 50V would be fine.

    Here is a part that would probably suit. It would require a small heatsink.

    That page has a datasheet for the device and there are typical circuits for this device. Note that the filter capacitor I mentioned above is additional to those shown on the circuits that are powered from a DC rail.
     
  3. paul60

    paul60

    22
    0
    Dec 11, 2010
    Do you have a circuit for this ? very new to electronics
    or where i can find a circuit
    thanks paul
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,178
    2,690
    Jan 21, 2010
    See Figure 10. Add a 470uF 50V (or higher voltage) capacitor in parallel to the 0.33uF one shown.
     
  5. mav2541015

    mav2541015

    3
    0
    Dec 20, 2010
    you're looking for a 7824 voltage regulator, use heat sink compound and a heatsink! that is the right part by the way.
     
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