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Regulated Power Supply

Discussion in 'Power Electronics' started by Sloan5556, Mar 19, 2015.

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  1. Sloan5556

    Sloan5556

    10
    3
    Mar 8, 2015
    Hello,
    I just bought a used CSi/Speco regulated power supply, 13.8 DC v. @4 amps, and I want to make it into and adjustable voltage power supply. I was thinking of hooking a potentiometer to it to adjust it. I was looking on the internet about this but all I have found so far are "build your own" versions on a breadboard or pcs.
    Are there any diy projects for this? Or what do I need?
     
  2. davenn

    davenn Moderator

    13,585
    1,870
    Sep 5, 2009
    hi there
    without knowing the circuit inside , that is difficult ( if you want it as an internal part of the PSU)

    2 easier ways to go for this
    1) easiest ... build up a variable unit on the outside of the existing PSU so you have

    existing PSU ---> small box with adjustable circuitry in it ---> on to what ever projects you want to use it with

    2) IF there is room inside the existing PSU box, you could mount that circuit in there and the voltage adj knob through the front wall of the case

    for the adjustable regulator, this one would be a reasonable choice ..... LM338K
    http://pdf.datasheetcatalog.com/datasheet/SGSThomsonMicroelectronics/mXuuvz.pdf

    circuit ideas down the page

    or you could go the DC-DC converter style like .....
    http://www.ebay.com.au/itm/DC-4V-38...y-Buck-Module-24V-12V-9V-5V-New-/380807562147

    the blue trimpot on there could be replaced by a larger pot mounted through the case


    cheers
    Dave
     
  3. Kiwi

    Kiwi

    322
    74
    Jan 28, 2013
  4. davenn

    davenn Moderator

    13,585
    1,870
    Sep 5, 2009
    That would work if he wants to go up in voltage

    Im picking he wants to take the 13.8V and be able to adjust it from between near 0V and 13.8V ;)

    and that will work with either of the 2 suggestions in my previous post

    @Sloan5556 please let us all know your intentions so we are no longer guessing

    cheers
    Dave
     
  5. Sloan5556

    Sloan5556

    10
    3
    Mar 8, 2015
    Here are some images of the inside and out. I want to have it so I can say change the speed of a motor or some thing similar.

    100_0067.jpg 100_0073.jpg 100_0076.jpg
     
  6. davenn

    davenn Moderator

    13,585
    1,870
    Sep 5, 2009
    OK cool pix :)

    changing the speed of a motor is a little more complicated that just changing the voltage
    specially if you wish the motor to have the same turning power ( torque)
    for this a PWM ( Pulse Width Modulation) driver and an H-Bridge circuit are required

    google those terms and see the ideas, come back with any questions and give links to the pages you were looking at that you didn't understand what was happening :)

    Dave
     
  7. Sloan5556

    Sloan5556

    10
    3
    Mar 8, 2015
    Thanks Dave.

    Funny, I was just watching this video a few days ago about PWM, .
     
  8. Colin Mitchell

    Colin Mitchell

    1,417
    312
    Aug 31, 2014
    You will only get 0v to about 12.5v
     
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