Step 12: Build a power supply

Picture of Build a power supply
A couple of years before we built the LED cube, we made our self a nice little lab power supply from an old external SCSI drive. This is what we have been using to power the LED cube.

PC power supplies are nice, because they have regulated 12V and 5V rails with high Ampere ratings.

You can use either a regular AT or ATX power supply or and old external hard drive enclosure.

If you want to use an ATX power supply, you have to connect the green wire on the motherboard connector to ground (black). This will power it up.

External hard drive enclosures are especially nice to use as power supplies. They already have a convenient enclosure. The only thing you have to do is to add external power terminals.

Power supplies have a lot of wires, but the easiest place to get the power you need is through a molex connector. That is the kind of plug you find on hard drives (before the age of S-ATA).

Black is GND Yellow is +12V Red is +5V

Here is an image of our lab PSU. We have 12V output, 5V output with an ampere meter and 5V output without an ampere meter. We use the second 5V output to power an 80mm PC fan to suck or blow fumes away when we solder.

We won't get into any more details of how to make a power supply here. I'm sure you can find another instructable on how to do that.
Most smartphone chargers are 5V 1A, I don't see why those would not work.
garet14 years ago
does a cell phone power supply (charger) suits for the cube? For example I have few 3.7V 355mA chargers. Can I use them to power up my cube?
Unfortunately that won't quite cut it.

You may have upto 64 LED's on at any one time with this cube - if we say that each LED is drawing say 10mA then you're looking at 640mA.

The lower value of resistor you use, the more current it will draw.

I think you would at least want a supply capable of 1 amp.

Normally Digital circuits run on a 5volt supply. Although you will find alot of microcontrollers and TTL chips will be happy to run off 3.7v
Perhaps if you were making a smaller cube. 5x5 may have a small enough draw, 4x4 almost certainly would.
Jwoozy2 years ago
Is there any step that shows you how to use the power supply. Explaining how the power supply is used to power the led cube?
Geekaton2 years ago

I am building the cube at the moment for a school project. Can anyone give me a link of where I can buy one of those power supplies you have up there?

If you have an old desktop computer stashed in a closet or something, you can pull the regulated power supply out of that in about 2 minutes. Most supplies will have 3.3V, 5V, and 12V outputs minimum, giving you a very versatile power supply for (basically) free.