This project is not an easy build to say the least, nor is it a cheap thing that you can slap together with random electrical parts. The LEGO construction was a heavily-modified project that went through a ton of revisions in both the 3D program LEGO Digital Designer, as well as in real life. As a result, the physical LEGO portion of this project via the LDD file may differ slightly than what you see in the final outcome, and if you attempt to build one yourself, you may notice a few differences.
The electrical system seems rather tricky, but is actually somewhat simple, if you have a basic understanding of soldering/wiring. The "brain" of the project is actually a model railroad traffic signal controller that I purchased on eBay, and then ultimately wired into the infrastructure of the traffic lamp. The light bulbs are pricey LED spotlights that use very little electrical power yet have a strong illuminated output. In simple terms, the LEGO structure serves as a house, inside the "house" are three spotlights each rigged up to a microchip which cycles through the colors like a real traffic light, and the front of the "house" uses a grid of colored transparent LEGO pieces which act similar to a Lite Brite set (or almost resembling a cluster of LEDs lit up). This "Lite Brite" system was covered in my popular Mosaic LEGO Lamps tutorial, which explains the principles behind colored light grids.
Like my other LEGO projects that I encourage fans to duplicate and make changes upon, this particular model can be altered according to your desire. You can forgo the whole electrical portion I've built and instead incorporate an Arduino system and control it via your computer. You can even mess with the colors or design, such as making the green light into a green arrow. It's all up to you.
- LEGO Digital Designer (free download) - 3D CAD program for making custom LEGO models - officially produced by LEGO Group, and not a third party program.
- My Traffic Light Signal LDD file (hosted on my site) - download the above program and import this model, which has its own 3D building guide included within. Here's a mirror link on my Google Drive. The instruction guide and parts list in an HTML format slideshow can be seen here.
- SuperBrightLEDs.com - a superb website for purchasing LED bulbs. The particular lights I used in my model can be found directly here - 48SMD-LED MR16, cool white, $9.95 each. You'll need three of them if you plan on making a direct duplicate of my design. I would highly recommend getting the solid white 6,500K bulbs, as they have great brightness, as opposed to the red, amber, and green lights (of the same product), since they're sort of dull. If you purchase these lights, you'll need this specific type of base to house the bulb (you'll need three, of course). These particular bulb sockets have two small holes drilled into them, which are just the right clearance of being penetrated by a LEGO antenna or pin, which you'll see later when assembling the whole shebang.
- BrickLink.com - at this point I'll make the assumption that you're a highly skilled master LEGO craftsman, thus this link is pretty self-explanatory. For those of you out of the loop, Brick Link is a huge online "candy store" for new and used LEGO pieces. My LDD file for the traffic light contains a full list of parts; just to give you a fair warning, this project -- according the LDD file -- contains exactly 1,779 LEGO pieces. If you're a novice builder and lack the patience and ability to sit through assembling a titanic model of this caliber, I would not recommend trying this. Also keep in mind that more LEGO bricks also equals more spending. Albeit this structure is pretty straightforward and requires a lot of simple masonry and engineering techniques, as opposed to something crazy elaborate like my LEGO Nintendo 64 Transformer. The LEGO portion of this traffic light is basically one really big yellow box with a door on the back, to be blunt.
- Model Railroad Traffic Light Control Circuit - I personally chose a pre-assembled DC version of this item, to save time, and so that it could easily be modified to potentially become portable and run on batteries. The AC version is slightly more expensive but can use larger 120V light bulbs with a greater amperage rating. The DC version is cheaper, but is limited to smaller bulbs like LEDs -- hence why I chose them; also because lower-voltage bulbs tend to have lower output power and would have less a chance at melting my LEGO bricks. The DC controller required an AC adapter (12VDC output) to be spliced into the screw terminals you'll read about that on step 2).
- Radio Shack - you'll need the following things to mimic my design verbatim: on/off toggle switch, 22 or 20 gauge wire, soldering iron/gear, 12VDC output 120VAC input adapter, and small spade and ring terminals.
I'll keep the assembly steps pretty straightforward, with some notes on the LEGO construction portion and a very basic schematic to go along with.