Power Supplies

Controllers are necessary, but they are useless if they don’t have any power. As such, we needed some power supplies to take 120V AC power from the wall and efficiently turn that into 12V DC power (and sometimes 5V DC power) to drive the pixel controllers and the pixels.

We did not appreciate when we started our adventure with pixel lighting just how challenging power management can be. 12V power does not travel very far down wires without losing voltage and 5V power is even worse. At best, pixels look bad when underpowered (whites turn yellow); at worst, they behave very erratically and become unresponsive. Make sure you get enough power to your pixels through properly sized power supplies and power injection. Check out this page on power injection to read about our challenges and how we overcame them. #TODO

“Big” Power Supplies

Where we need serious amounts of power, we use fan-cooled switching power supplies designed for CCTV systems, ham radio, and other similar things. As far as I can tell, there are about 100 different people selling these things and they are all more or less identical. We paid about $20 each for our two 12 volt 30 amp power supplies on Amazon.

The E682 pixel controller isolates its outputs into two groups of eight and thus you need two power supplies to fully drive the pixel controller. If you have 8 or fewer universes, then you could get away with just a single power supply and leave the other half of the controller unpowered.

The power supplies also are the source for the power we send for power injection. We use terminal blocks to make connecting lots of wires easier. I’m not sure how much it actually matters, but people online have indicated that any given universe should get power from only one power supply. When doing power injection, then, make sure that you run the wires from the correct power supply. These supplies are not meant to have their V+ terminals connected together (though you should connect the V- so that there is a common ground across the system).

These supplies often have a toggle switch on the side to choose the input voltage between 110 and 220 volts. Ours was defaulted to 220 volts, which is not correct for the USA. Make sure you select the correct input voltage on the supply BEFORE plugging it in to avoid any possible damage.

NOTE: One of the possible deficiencies in our system is a lack of fuses in the power injection lines. I’m not sure what the risk in that is (maybe destroy up a power supply) but you might consider fusing those lines. It is also worth thinking about whether a GFCI outlet should be used for the circuit, though we don’t do that ourselves at this time. I had intended to do this but we had some issues with the fuses being too long for the fuse holders and I gave up on it. The pixel controllers already fuse each of the lines they send to the pixels.

Garage Door Power Supply

The seven-segment displays mounted on the front of the garage door run at 5V so we purchased a 5V 40A power supply on Amazon to drive them. It looks and feels just like the 12V versions.

“Little” Power Supplies

The window boxes require much less power and are physically separated in different rooms of the house. Since we want them to be a inconspicuous as possible, a fan-cooled power supply is not a good option due to the noise it makes. Fortunately, each light box only requires a few amps of power and we are able to use some standard “wall wart” power packs and “box on a string” power packs (like what is used for laptop computers). The supplies we use range from 2A to 5A.

One unexpected challenge we faced was finding inexpensive power packs like these that are truly UL listed. It’s nearly impossible to find this kind of equipment manufactured anywhere other than China and the risk of receiving counterfeit merchandise is higher than we would like. Ultimately, we did our best to read reviews from other people who had purchased these items and stayed away from the ones that seemed particularly risky.

Another consideration when dealing with lots of power supplies is the risk of radio frequency interference. In theory, consumer electronics should be UL listed and approved by the FCC and tested to not cause RF interference. The proliferation of counterfeit goods makes this a lot less certain. Several reviewers on Amazon who were buying power packs for ham radio purposes commented that some of the items they received caused so much interference that they were unusable.

We have not seen any noticeable interference on our FM broadcast, however, we have noticed that the garage door remote works far worse in December than any other time of year. Normally, we can open our garage from the entrance to our street 2 houses down. When everything is plugged in for our Christmas display, we need to be at the base of the driveway for the garage door remote to work and even then it is finicky. We don’t know if it is one rogue power supply that is causing the interference (or some other component) or if it is the cumulative effect of everything we have going. It is inconvenient but ultimately only a minor issue and thus we haven’t spent any time investigating the root cause.

Power Injection

We can’t talk about power supplies without also talking about power injection. In fact, we have an entire page dedicated to it: All About Power Injection