Looking for some LED lights a while back, I came across some acrylic light globes; the kind that you find on stair landings in apartment buildings. I noted that they came in various sizes, from around 8” up to 30” and beyond. I realized that you could put three globes together and make a decent snowman for very little cost. So, I ordered, a 14”, 12”, and 10” spheres, and each of them has a 5 1/4” hole in the bottom. They stack up nicely:
That gives me a snowman about 3’ tall. The next question is, “what do I do with him?”
Well, the first part is that it’s obviously going to be lit up, and it’s also going to use LEDs to do it. Having worked with a number of project before, I’m not really excited to build another 8 or 16-channel custom controller along with the associated electronics and cabling; it’s a lot of grunt work. A *lot* of grunt work, and I only have 3-4 weeks to get this done.
I’m therefore going to leverage advantages of technology, and instead of going with individual LEDs, I’m using WS2812 LEDs. These amazing little devices are an integrated RGB LED + controller, and you just chain them together. So, instead of running a bunch of different wires, I can daisy-chain each LED together. I can then hook up the end to a microcontroller and address all of them individually.
I’m going to start with a meter of LED strip, which has 60 individual LEDs. I’ve chosen to buy it from Adafruit, because I like what they do:
You can definitely find cheaper versions elsewhere; I’ve seen some on ebay less than $10, though they aren’t waterproof (I don’t really need the waterproofing for this ). The strips can be cut apart between the leds, so you can think of this as 60 individual easy-to-wire-together LEDs rather than one big strip.
I also picked up some individual ws2812 pixels (the black part is the driver chip):
and some diffused 8mm pixels:
All of these use the same technology and can be hooked together. Once again, the individual leds are cheaper elsewhere if cost is a big issue. I know some people who wanted large quantities have ordered them through aliexpress.com and gotten them much cheaper.
Driving them does take a good 5V supply, and you are the wiring you use to hook the +5V and ground wires together. If you get to bigger lengths, you have to provide power in the middle. If you are using an arduino – as I will – you are also limited by the memory of the arduino, since each pixel takes a byte. Neither are an issue for this project.
So, basically, the plan is to use put strips inside so that the illuminate the globe, and then do something for eyes/nose/mouth.
I haven’t decided how to light the interiors. I found that just putting an array of leds at the bottom gave a nice overall glow, but I could also put a dodecahedron in the middle of the globe, which would give me 10 leds pointed all around the globe. Similar amounts of illumination, but it would give me the opportunity to animate the leds in interesting patterns.
I’m also working on how to hold them together. I could use simple 3-d printed clips, or I could use threaded rod up the middle. I think I’m leaning a bit towards sections of hollow threaded lamp rod; I could run the power & signal up inside them, and then could be used to hold the globes together as well.
Eyes/mouth/nose will be one of the following:
- A led pixel on the inside, which gives a little circle of light on the outside.
- An led pixel on the outside with a ping-pong ball over it as a diffuser
- An 8mm diffuse led through a hole with or without a diffuser.
#2 and #3 seem the nicest, and I’ll play around with them a bit.
So, what do you think ?