In the world of big-box retail, December 26th is a very special day. The Christmas music playing on the overhead speakers switches back to the family friendly Top 40, the store’s decorations get tossed in the compactor, and everything that’s even remotely related to the holiday is put on steep clearance.
No more money to be made on the most commercialized of all holidays, so back to business as usual.
It’s in this narrow corridor of time, between the Great Holiday Unloading and the new spring products coming in, that you can find some fantastic deals on Christmas decorations. Not that long ago, this would hardly be exciting news for the readers of Hackaday. But Christmas lights and decorations have really started pushing the envelope in terms of technology: addressable RGB LED strands, Bluetooth controlled effects, and as of the last couple years, friggin’ lasers.
That’s right, you’ve seen them all over the neighborhood, probably took a few stray beams to the eye, you might even own your own. Laser projectors have been one of the most popular Christmas decorations for the last couple of years, and it’s not hard to see why. Just set the projector up in front of your house, and you’re done. No need to get on a ladder and string lights on the roof when you can just blast some directed energy up there instead.
Given how popular they are, I was surprised to see a lone Home Accents Holiday Multi-Color Light Projector on the clearance rack at Home Depot for around $14 a few days after Christmas.
This was a 75% price reduction from normal MSRP, and right in that sweet impulse-buy price range. Let’s see what’s hiding inside!Cracking it Open
This particular projector isn’t much different from other’s I’ve seen, except for the fact that it actually has three lasers inside. Usually these projectors are just packing red (662 nm) and green (532 nm), but this one has a blue (440 nm) laser as well. Interestingly, there are only two laser apertures in the front of the unit, which means there must be some kind of beam combiner inside that’s allowing two of the lasers to shoot through one window. Presumably it was cheaper and easier to tack a beam combiner into the design than get new cases injection molded.
Four screws on the back of the unit allow you to pull off the cover, which I was somewhat impressed to see had a decent rubber seal around the edge to keep water out. With the back cover off you notice the first interesting element of this projector’s design: the external heatsink.
I had wondered why they used a metal “knuckle” on the mounting stake, and assumed that the finned design of the piece was just to reduce the material needed. But as it turns out the knuckle is connected directly to the primary laser heatsink by means of a solid metal cylinder, they even put a little bit of thermal conductive material on the mating surfaces. It’s not perfect, but at least it gets some thermal mass outside of the airtight body.
Getting a Closer Look
After removing the external heatsink, the “sled” containing all of the internal hardware slides easily out the back. All of the components of the device are easily accessible, and they’ve even gone as far as using connectors for most of it instead of soldering everything directly to the PCB in the back. It’s like they wanted us to strip it for parts.
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