Power Supply with an ATX PSU

Description

Create a lab Power Supply from an ATX PSU.

Components

Shop	Article N°	Description	Unit price (CHF)
Distrelec	100538	Laboratory socket black ø 4 mm	4.-
Distrelec	100540	Laboratory socket red ø 4 mm	4.-
Distrelec	100546	Laboratory socket green ø 4 mm	4.-
Distrelec	100544	Laboratory socket yellow ø 4 mm	4.-
Distrelec	100542	Laboratory socket blue ø 4 mm	4.-

Price

Depends of connectors number and of availability of an old working ATX PSU.

Voltage

• +5VDC
• +3.3VDC
• +12VDC
• -12VDC

People involved

• Fred
• Speredenn

Links

http://www.semageek.com/diy-transformer-une-alimentation-atx-en-alimentation-de-laboratoire/

http://pinouts.ru/Power/atxpower_pinout.shtml

http://www.sinux.net/2011/09/alim-atx.html

http://www.instructables.com/id/How-To-Build-A-Power-Supply-For-Electronics-Hobby/

Pictures

Update: PSU with regulate output

It is a better idea to have the ATX set up in a box and to use the ATX connector to connect to the banana plugs. Basically, it is then possible to have the 5 usual plugs (GND, +3.3, +5, +12, -12) and add a regulated output (0-12V). The visualization for that regulated output can be analogical. However, if the system uses a micro-controller (see Buck converter below), a digital screen could be an option. That would also be great to have a current limiter on that regulated output.

Linear regulators are excluded for this improvement because they dissipate way to much energy. A switch-mode power supply approach is favored. So far, a Buck converter is considered.

Options

I suppose it is good to have at least 2 LEDs, a red and a green, each with a 220Ω resistor in series. turning on the PSU can be done with a SPDT switch, that is: on1 - on2.

• red LED is between on1 and purple (standby 5V)
• green LED is between grey (power OK) and on2 (or GND, for that matter)
• green cable is soldered onto on2
• middle point of the SPDT switch is on GND

this has the following consequences:

• when PSU is on mains and switched off, the red LED is on
• when flipping the switch, PSU turns on ; after about a second the green LED lights, indicating all is good.

I feel like wasting time, so here's some crappy ASCII art for this:

green-----------------
            (grn)    |
grey----R----|>|--o  o--------ON2
                  |          /      ←{ this here is the SPDT switch }
GND---------------o--------o/
            (red)
purple--R----|>|--------------ON1

Components

Shop	Article N°	Description	Unit price (CHF)
Distrelec	679017	24-pin (NT) – 20-pin (MB)	12.-
Distrelec	100536	Laboratory socket light-gray ø 4 mm	4.-