Instructables

OMAPS - One More ATX Power Supply conversion

Step 5: Connecting the wires

Picture of Connecting the wires
10) Connect one of the red wires to the power resistor.
11) All the remaining red wires to the red binding posts.
12) Connect one of the black wires to the other end of the power resistor.
13) One black wire to a resistor (330 ohm) attached to the anode of the LED(see the next image)
14) One black wire to the DC-On switch
15) All the remaining black wires to the black binding post.
16) Connect the white to the -5V binding post, yellow to the +12V binding post, the blue to the -12V binding post, the gray to the cathode of the LED.
  • Note that most power supplies have either a mauve or brown wire to represent "power good"/"power ok". Check the ATX plug (the plug with many connections) to see if there is a small mauve or bown wire plugged into the same hole as an orange wire (+3.3V) or a red wire (+5V). If the small wire is connected to the orange in the ATX plug then do the same, hook these two together. If it is connected to the red, then hook it to the red wire. This wire must be connected to either an orange wire (+3.3V) or a red wire (+5V) for the power supply to function. When in doubt, try the lower voltage first (+3.3V).
 
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samumar2 years ago
Hello and nice instructable!
I liv e in Europe and using 220V AC input.
Do I have to change the 10 ohm 10 W resistor with some different resistor or is it good using the same?
I need 6 amp out in the 12V line!

Thanks a lot!


Sam
pro52002 years ago
I have a PSU from my old computer pentium II, I have connected the red and black wires to the power resistor, and green wire to black wire I connected to the switch, my PSU have 5 brown cable & just 1 brown cable connected it to orange cable, but the psu still would not start, can you help me?
Exiumind2 years ago
I'm trying to use a computer psu to power up a rgb led strip(12v, 3amp)..
The 12v rail is giving 12.4v (no load), the outputs of these psu's arn't regulated right?
If i use a high current voltage regulator i'l get a fairly large voltage drop, and that wont give me the full 12v i need.. the only v reg i have right now is a sharp pq12rd11, since it has low Vd, the output i get is around 11,9v.
What do you think, should i use this one and some transistors to handle more current?

Need some tips guys =)

abizar (author)  Exiumind2 years ago
The RGB strip will work when connected to the 12 V end. More than 3 amps should be available on most PSUs. If you do want to drop voltage an easy way is to put a diode in series. A silicon diode will drop about 0.6-0.7V. Make sure that the diode is rated to handle the current.
Exiumind abizar2 years ago
the point is that i want to use the computer psu that puts out 12,4v or so, and with this regulator the problem is that even having a low Vd it only supplies 1 amp max..

anyway, ill powerup the stirp using just the regular 12v output
houssemus3 years ago
hi, i am quite beginner,!
what's the rule of the power resistor!
brod4 years ago
Hi Should that be in step 13 that the grey wire has the 330 ohm resistor and not the black one, also the black wire should go to the cathode and the grey one to the anode.
Laminarin4 years ago
You might also use a fan as a load in place of the 10 Ohm resistor (if you can find a 5v 500 mA fan). Then you still have the same current (5v / 10 Ohms = 0.5 A = 500 mA) load but you also get some cooling instead of more heat.
abizar (author)  Laminarin4 years ago
Had tried that but the regulation on 5V was erratic - would vary from 4.1V to 5.2V