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Convert/adapt an old ATX Power Supply into a Bench Power Supply with (or without) 3D Printed Parts

Posted by jpluimers on 2018/11/16

An interesting idea, although I would slightly modify it so I can -12V and -5V as well and maybe other voltage combinations too:

They are based on these underlying links:

Note that some of the newer power supplies with 24-pin molex connectors do not give you -5V any more.

A few notes:

  • depending on the age, ATX supplies can get you these voltages: -12V, -5V, 0V, +3.3V, +5V, +12V
    • -12V and -5V have very limited currents
    • newer power supplies often do not have -5V (especially the ones having 24-pin connectors)
    • newer power supplies have limited +5V power, but higher +12V power
    • older power supplies have limited +12V power, but higher +5V power
  • always take pictures of all connectors and the wire colours connected to them before starting (especially before cutting any wires)
    • this allows you to find back:
      • non-standard wire colours
      • configurations not covered here
  • to get stable 12V, you need a 5V load of about 5W:
    • between RED (+5V) andBLACK (GND),
    • for instance with pin 3 and pin 4,
    • or over one of the molex/floppy connectors: pins RED-BLACK
    • as load,
      • use at least a 10V/10W resistor or 12v/10W halogen lamp
      • ensure they are cooled well
  • to get stable 12V, you need a 12V load of about 10W
    • between YELLOW (+12V) andBLACK (GND),
    • for instance with pin 10 and pin 17,
    • or over one of the molex/floppy connectors: pins YELLOW-BLACK
    • as load,
      • use at least a 20V/20W resistor or 12v/20W halogen lamp
      • ensure they are cooled well
  • if your power supply has a BROWN (+3.3VS),
    • then ensure it is connected to ORANGE (+3.3V)
      • as brown is the SENSING wire to check 3.3V is OK.
  • to turn the power supply on,
    • short GREEN (PWR_ON, pin 14) and BLACK (GND, pin 15)
  • to know when the power is on:
    • connect a LED via a resistor between GREY (PWR_OK, pin 8) and BLACK (GND, pin 7)
  • to know when there is mains power:
    • connect a LED via a resistor between PURPLE (+5VSB, pin 9: stand by) and BLACK (GND, pin 7 or pin17)
  • Wikipedia: ATX Power supply describes
    • PWR_OK (often called Power Good)
    • +5VSB (stand by)
  • read the specs of your power supply to understand how much current it can deliver on which lines
  • some more current information

Example for loads: https://www.youtube.com/watch?v=gKgziA46wFY; more on why you need them and how to choose:

With a few more modifications you can [WayBack] Convert a Computer Power Supply to a Variable Bench Top Lab Power Supply.

I will probably go for this solution as it is easier to swap power supplies.

–jeroen

Via: [WayBack] Nice recycling of an old ATX power supply with a 3D printed part and a few accessories and cables… – Jean-Luc Aufranc – Google+

 

[WayBack] Using PC power supplies in things other than PCs

Via: [WayBack] What is the power specification for SATA?

Details:

PC Power Connectors

 

How to Convert ATX PSU (PC power supply unit) into a cheap bench top power supply which can be used to power many different types of electronics circuits

20 pin molex connections

Pin Name Colour Description
1 3.3V Orange +3.3 VDC
2 3.3V Orange +3.3 VDC
3 COMMON Black Ground
4 5V Red +5 VDC
5 COMMON Black Ground
6 5V Red +5 VDC
7 COMMON Black Ground
8 Pwr_Ok Grey Power Ok (+5 VDC when power is Ok)
9 +5VSB Purple +5 VDC Standby Voltage
10 12V Yellow +12 VDC
11 3.3V Orange +3.3 VDC
12 -12V Blue -12 VDC
13 COMMON Black Ground
14 Pwr_ON Green Power Supply On (active low)
15 COMMON Black Ground
16 COMMON Black Ground
17 COMMON Black Ground
18 -5V White -5 VDC
19 5V Red +5 VDC
20 5V Red +5 VDC

24-pin molex connections

Pin Name Colour Description
1 3.3V Orange +3.3 VDC
2 3.3V Orange +3.3 VDC
3 COM Black Ground
4 5V Red +5 VDC
5 COM Black Ground
6 5V Red +5 VDC
7 COM Black Ground
8 Pwr_Ok Grey Power Ok (+5 VDC when power is Ok)
9 +5VSB Purple +5 VDC Standby Voltage
10 12V Yellow +12 VDC
11 12V Yellow +12 VDC
12 3.3V Orange +3.3 VDC
13 3.3V Orange +3.3 VDC
14 -12V Blue -12 VDC
15 COM Black Ground
16 Pwr_ON Green Power Supply On (active low)
17 COM Black Ground
18 COM Black Ground
19 COM Black Ground
20 -5V White -5 VDC
21 +5V Red +5 VDC
22 +5V Red +5 VDC
23 +5V Red +5 VDC
24 COM Black Ground

 

 

3 Responses to “Convert/adapt an old ATX Power Supply into a Bench Power Supply with (or without) 3D Printed Parts”

  1. DJEBLI said

    Good work
    To protect the ATX again short circuit. It will be better to connect the Green wire (power on) to Relay contact with black wire. And to energize the relay with the 12 v or 5 v accorditly.

  2. Dominik Kwolczak said

    Seems very interesting!

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