The Wiert Corner – irregular stream of stuff

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

• [WayBack] Convert an old ATX Power Supply into a Bench Power Supply with (or without) 3D Printed Parts.
• [WayBack] Benchtop power supply with ATX connector

They are based on these underlying links:

• [WayBack] ATX to Benchtop Power Supply by elliotboney – Thingiverse
• [WayBack] Convert ATX PSU to Bench Supply to Power Circuits

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
  • [WayBack] Power spec for the PCI-E 8 pin power plug – [Solved] – Components
    • PCI-E 6 pin: Pins 1 & 3 are 12V & each can carry 8 A, totaling 12V*8A*2= 192W
    • PCI-E 8 pin: Pins 1,2,3 are 12V & each can carry 8 A (before ~ March 2005) or 11 A (after ~ March 2005), totaling 12V*8A*3=288 W or 12V*11A*3=396W
    • It also explains why not all pins in these connectors are connected or can carry current.
  • Not just the connector, also the wires matter: American wire gauge: Tables of AWG wire sizes (and A rating)
  • To get a feel read [WayBack] Using PC power supplies in things other than PCs and the pages he links to (see list further below)

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

• [WayBack] How to calculate suitable dummy load for a power-supply?
• [WayBack] PC Power Supply – Power supplies (PSUs) built for commodity PCs, typically ATX PSUs – Base Load
• [WayBack] ATX power supply 5V load resistor for better 12V regulation
• [WayBack] Converting an ATX Power Supply Into a DC Bench Supply
• [WayBack] ATX to Lab Bench Power Supply Conversion
• [WayBack] ATX Based Lab Power Supply
• Don’t choose the wrong resistor… [WayBack] Convert an ATX Power Supply Into a Regular DC Power Supply!

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?

• [WayBack] Using PC power supplies in things other than PCs
• [WayBack] Compatibility issues for ATX power supplies and motherboards
• [WayBack] A short history of PC power supply voltage rails
• [WayBack] So what’s all this rubbish about multiple 12 volt rails?
• [WayBack] All about the various PC power supply cables and connectors
• [WayBack] Rail complications #1 – current limit problems: too much current
• [WayBack] Rail complications #2 – cross loading problems: unbalanced current
• [WayBack] Rail complications #3 – minimum loading problems: too little current

Details:

• [WayBack] All about the various PC power supply cables and connectors (it has tables with the various part numbers including ones for parts of connectors and unofficial current/wattage that I’ve quoted below)
  • [WayBack] oldpc: Original PC main power cables
  • [WayBack] peripheral: 4 pin peripheral power cable
    5A per line; one 5V line; one 12V line
    (The connector is often called “Molex”, but actually is AMP Mate-N-Lok; Molex has tons of different connects, one of which is now compatible with the AMP one)
  • [WayBack] floppy: Floppy drive power cable
    3A per line; one 5V line; one 12V line
  • [WayBack]aux: 6 pin auxiliary power cable
    10A per line; two 3.3V lines; one 5V line
  • [WayBack] sata: SATA power cable
    1.5A per line; three 3.3V lines; three 5V lines; three 12V lines
    (3.3V is often not connected)
  • [WayBack] atxmain20: ATX 20 pin main power cable
    6A per line; three 3.3V lines; four 5V lines; one 12V line
  • [WayBack] atxmain24: ATX 24 pin main power cable
    6A per line; four 3.3V lines; five 5V lines; two 12V lines
    (most PSU with the 24-pin connector omit the -5V lead from it)
  • [WayBack] atxmain20plus4: ATX 20+4 pin main power cable
    6A per line; four 3.3V lines; five 5V lines; two 12V lines
  • [WayBack] atx12v4: 4 pin ATX +12 volt power cable
    8A per line; two 12V lines
    (note it looks similar to the “plus 4” from the “20 plus 4”, but is different as the 12V4 has only 12V)
  • [WayBack] eps8: 8 pin EPS +12 volt power cable
    7A per line; four 12V lines
  • [WayBack] eps4plus4: 4+4 pin +12 volt power cable
    7A per line; four 12V lines
  • [WayBack] pciexpress: 6 pin PCI Express power cable
    8A per line; two 12V lines (sometimes three 12V lines)
  • [WayBack] pciexpress8:
    8A per line; three 12V lines
  • [WayBack] pciexpress6plus2: 6+2 pin PCI Express power cable
    8A per line; three 12V lines

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

24-pin molex connections