October 20th, 2015
  • Provide power-demanding devices
  • Easy turn on / off power
  • Automatic failure recovery

Power source library

I've made it my quest to create OOP classes for Arduino. Read about that in this blogpost if you need some more context.

This class is to control a PC power supply in order to provide power-demanding devices in your setup.

Since 1993 all power supplies have an ATX plug. This plug can have 20 or 24 pins or it can be a hybrid, containing a 20 pins plug and a 4 pins plug that can be linked together, like the one on this photo:

From this plug we need the green wire, the purple wire, the gray wire and a black wire. For the black wires it does not matter which one you choose, all black wires are ground. If your ATX connector doesn't have a gray wire, you can also connect one of the red wires to your Arduino instead of the gray wire. In that case it doesn't matter which red cable you take:

Scheme power source

Whenever the power plug is connected the purple wire is always 5V with a low amperage. This is more than enough to power the Arduino, but not to power a lot of extra devices.

See the example source here to control the power supply.

When you call the turnOn() method the power source is turned on, and these wires are powered with a higher amperage:

Wire colorVoltage
Orange+3.3V DC
Red+5V DC
Yellow+12V DC
Blue-12V DC

The gray wire (or red wire if you don't have a gray wire) is +5V when the power supply works as expected. In case the power supply stops working as expected, for example due to an overload protection, the library will automatically reset the power supply.

The power source library can be found here on GitHub.
It uses the BaseTimedElement base class which can be found here on GitHub.

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Hi Scotty, I'm not sure... when I check your url you've provided I see wires coming out of the unit, but the DELL site shows the unit without any wires: http://accessories.dell.com/sna/productdetail.aspx?c=us&l=en&s=gen&sku=450-aebl Does your unit have wires? Otherwise it will be way more difficult; maybe you can start your search here: https://www.google.nl/search?q=hot-plug+power+supply+pinout&tbm=isch#imgrc=3ACsNcI_JW6WZM%3A I have no experience with those units...
Laurens Huizer, December 15th, 2015
Hello! MAny thanks for this post! It is very useful for me! I have a problem with my power supply. It is Dell hardware.nl/power-supply/dell/450-aebl.html, could you tell me, does your tutorials are appropriate for this model. I will be very happy if it is exactly what I searched for!
Scotty W, December 15th, 2015

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