Power supply for the experts

Discussion in 'The Projects Forum' started by Slanwar, Mar 7, 2015.

  1. Slanwar

    Thread Starter New Member

    Mar 7, 2015
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    I want to build a power supply (I know buying one is cheaper) and I'm not using a computer ps because I already have one. The project:
    Output with a range from 3 volts to 30.
    I will add 2 digital panels to read amps and volts.
    What I need;
    Transformer (need specs here)
    Voltage regulator (LM317?)
    Can someone design a schematic for me with all the values and what I need?
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Roderick Young likes this.
  3. Slanwar

    Thread Starter New Member

    Mar 7, 2015
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  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,493
    2,363
    They show the common connected to earth ground, you may want to float it if a bench supply?
    Max.
     
    planeguy67 likes this.
  5. crutschow

    Expert

    Mar 14, 2008
    12,972
    3,219
    The amount of output current you want will determine the size of the heat sink you will need for the LM317.
    For example with a 1A output at 3V and a 35V source, the power dissipated by the LM317 is 32W, which requires a large heat sink. For that you might consider adding a cooling fan to reduce the size of the sink or a heat sink with a integral fan like those used for cooling PC processor chips.

    The transformer should have a current rating about double of the maximum DC current you want.
     
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