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Making a standalone 12v power supply rom a PC ps...

Discussion in 'Technical' started by Gun Nut, Oct 26, 2009.

  1. Gun Nut

    Gun Nut Proud Veteran

    Making a standalone 12v power supply from a PC power supp...

    I'm toying with the idea of making one to power a small car amp to run my MP3 player through at work.

    I know, I know. There are already things made to amplify audio from MP3 players for listening without headphones. But they cost a bit more than I'd like to spend. I figure I can make one for around $10 (I already have the amp and power supply)

    I've read up on it a bit elsewhere on the web, and it seems alot of the RC plane guys build them to power their RC battery chargers. Doing the math, a 170 watt amp will draw about 14 amps, and a 200 watt computer ps should be able to output almost 17 amps. (both at 12v) I think I may need to sort through my PC boneyard box in the basement to find a bigger ps, but it all seems do-able... It's looking like I could also wire the 5v line to a USB plug to power the MP3 player to boot.

    Any thoughts, or has anyone made one of these before?
  2. Tango3

    Tango3 Aimless wanderer

    Just got back from barnes and noble.The latest "Make" magazine has an article (Pg139) where they created speakers for an mp3 player by attaching ear buds to the bottoms of disposable cups ...(don't know if they were plastic or wax paper cups.)
  3. Gun Nut

    Gun Nut Proud Veteran

    LOL I get the theory, but I doubt it would be audible in a machine shop environment!
  4. Tango3

    Tango3 Aimless wanderer

    Hey "3 fingers" you should be paying attention to the moving cutting tools, and hot flying chips![dunno][dunno]
  5. Gun Nut

    Gun Nut Proud Veteran

    Gotta have some music. A long night of just machine noise will put you to sleep real quick!

    Anyway, I got it figured out and built. Gonna test it out when I get home... I'll post a the test results and a "how to" later on...
  6. Tango3

    Tango3 Aimless wanderer

    countin' on it...:D
  7. Gun Nut

    Gun Nut Proud Veteran

    Ok, it works!

    HOW TO:


    1) Aquire an old power supply.
    2) Cut off all the plugs on the end of the wires, and sort them by color.
    3) Once they are sorted, strip and join all wires of the same color leaving out 2 black wires for later use.
    4) You will need to connect the green wire to one of the black wires you left out to get the power supply to power up. (you can also use this for an on / off switched circuit)
    5) Attach a 10ohm 10 watt resistor to the red wire(s) attach the other end to the second black wire you left out. This puts a load on the power supply raising the 12v output. (from 11.4 to 12.2 on mine)
    6) Attach to device you wish to power to the appropriate wire set. (Wire cap and tape off the wire sets not needed)

    Color key:(double check with a volt meter, this key is copied from the chart on MY ps, but it SHOULD be the same for yours)
    yellow = 12v , black is ground, red = +5v, white = -5v, blue = -12v, orange = +3.3, purple = +5vSB, Green = PS on.

    *note* I used an ATX supply if you're using an AT, in step 3 leave out only 1 black wire, and skip step 4 and the rest should be the same...

    Good luck!
  8. Gun Nut

    Gun Nut Proud Veteran

    I built another last night out of an old Xbox 360 power supply(200 watt model). works the same, just looks alot better when your done with it! It's also a little easier to do!

    This will give you 12v 16.5a power (using the 200w model probably less amps using the 175w model) this should be plenty to run a mobile CB and possibly a ham from the house.

    Remember I ain't responsible if you fry something! Use a meter to verify output before you hook it up!

    1) Remove the plastic cover from the end that connects to the Xbox.
    2) Push the pins out of the plastic connecter, then cut them all off.
    3) Strip and connect all the Yellow wires together.
    4) Stip and connect all the black wires together.
    5) Strip and connect the blue and red (some of these are purple instead of red). This turns on the 12v line and turns the light from yellow to green on the power supply.
    6) Connect to the device you wish to power.

    Yellow = +12v
    Black = Ground
    Blue = Power Enable
    Red (or purple) = +5vSB

    Here is a pic of the BACK of the connector...
    BACK of Xbox connector.
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