Introduction: Fully-Functional LEGO Traffic Signal Lamp
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.
Step 1: LEGO Structure Assembly/Resources
- LDD Free Download
- LEGO Traffic Light LDD file hosted on my website (mirror link on Google Drive)
- LEGO Traffic Light 3D illustration and parts list slideshow in HTML format hosted on my site
As you progress throughout the stages of this tall structure, you'll notice something rather odd about the internal colors: the inside walls have black bricks lined against the yellow walls: this is intentional, and was a last-minute addition to the design. Initially, the walls were originally 1x1 thick, and because of their bright color they would allow light to escape from the inside. In other words, the light from the spotlights would peek through the yellow walls -- hence I've reinforced them with a second layer of 1x1 bricks, only black, so make the traffic light appear totally opaque from the outside when lit up. Also in my final design of the project, I've lined the walls with metallic reflective duct tape.
The rear door has Technic bricks interlocking with stud-on-side 1x1 bricks; at first I assumed I would lots of these to keep the door shut properly, but upon actually building this, I realized the seal was too tight, and when pulled apart, some of the internal parts could come loose. Feel free to omit a few of these "buttons" that keep the door shut.
On the rear door, there are three ports to hold the LED lamps. The grey Technic pins are to be slid through the back, so that the lamp bases can connect. The four holes on the bottom of the door are where the pins to keep microchip controller in place shall rest, and above one of the holes is a blank square area (a missing brick): this is intentional -- because this is where the power cord will go through. Towards the top of the door you'll see another deliberately empty area, albeit reinforced with modified bricks. If you purchase the exact same toggle switch I provided a link to earlier, you should be able to slide the switch through the hole snugly. Make sure to calmly twist the threaded plastic part of the switch when placing it through the hole, so that it goes the whole way back.
If assembled properly, your structure will be sturdy, the door will open and close easily, the colored areas on the front will have enough transparent dots to make a circular pattern, and the rear door will have sufficient infrastructure for keeping electrical components in place. Try not to be so detailed-oriented when following the LEGO instructions: yes, I'm telling you to not pay too much attention to the LEGO build guide -- because chances are you're better off using your own keen sense of judgement and LEGO-engineering to construct a sturdy building -- with only using the 3D LEGO instructions as more of an "inspiration" or suggestion. What really matters is that your tower is of the proper size requirements, maintains necessary components for keeping the electrical parts intact, and above all, actually resembles a traffic signal! Feel free to deviate with the design as you please, and even feel free to make any size changes. You can make the traffic signal bigger than the model I've built, and you can play around with the physical design. My model provided in the 3D instructions serves more as a basic suggestion of making a standard sturdy structure for a LEGO traffic light, with the bare necessities for eventually adding electrical parts -- and not necessarily intended to be copied verbatim (although you're obviously free to build it exactly the same as mine if you choose)!However, the only parts I'm encouraging to copy verbatim are of course the ports for housing the electrical parts, because if you decide to use my exact electrical parts list (lamps, microchip, and all), you'll need certain areas of the LEGO structure built in precision to maintain the electronics! In other words, details like the sloped LEGO pieces on the roof or the colors of the base aren't mandatory -- but things like placing the Technic bricks in the right spot to have the microchip held firmly are however mandatory (assuming you're using the same microchip as me)! If you plan on deviating with the electronic parts, like using your own schematic and circuits, then of course make sure to have the LEGO structure built to reflect your changes -- such as, for instance, making the bottom base larger and hollow for potentially housing an Arduino circuit.
Step 2: Electrical Work
The electrical portion may seem rather tricky to someone with little or no electrical savvy, but if followed correctly, it's quite a breeze. Unlike the physical LEGO portion which was meant to serve as a general suggestion, the electrical portion on the other hand must be followed precisely to maintain functionality and safety. The schematic you see is a diagram provided as a guide if you plan on using my exact traffic light's size and functionality, which uses specific light bulb types, wire types, switch, power input, and microchip controller provided in the aforementioned resources on the first page. Again, I chose a specific model of a traffic light control module from a toy railroad; if you're rather skilled with microchips and electronics, feel free to use your own improvised system, such as an Arduino circuit and perhaps a series of relay switches, timers, and LEDs for a chasing light effect. You can even hack apart a Christmas light set if you please -- and if you know what you're doing! In fact, prior to when I purchased the traffic signal controller, my original idea was to take apart a Christmas light set and use its timer mechanism.
If you've purchased the DC microchip controller from Galak Electronics like I did, the four corners of the microchip have holes in them that fit snugly around LEGO bars/pins. Simply slide the microchip into place of the four Technic pins located on the bottom of the door, assuming you've spaced the holes out properly. The LEGO cones are then to go over top of the four pins to keep the microchip in place. Each lamp base should be held into place by the Technic pins throughout the middle of the doors. Refer to my schematic for soldering/crimping the wires into place: for example, the green lamp base should have one wire screwed directly into the green terminal, whilst having its second wire connected to the two other lamp sockets via ring/spade terminals -- and ultimately connected to the command wire, which goes into the command screw terminal. The red lamp socket is high up and may need some special soldering/crimping to extend its wires to the microchip and the command line.
The top switch should have two wires attached to it: one should go directly into the input terminal, whilst the other should be connected to a split cord from the DC adapter -- and finally, the second wire from the split DC adapter goes into the second power input terminal. If done properly, you've successfully made a complete circuit with a break switch to power on/off, and with a DC adapter for power. The DC wires from the AC adapter are polarized and must be screwed into the proper sides of the power terminal. If you've assembled everything properly and get no power, remove the two wire ends and swap their positions. As a rule of thumb, before installing this microchip into your LEGO project, always test its functionality and terminals first; test your AC adapter's wires in the microchip's power terminals, and remember which polarized wire goes in the proper screw terminal.
If you've purchased the same exact signal control chip as I have, you'll see a grey dial in the bottom left corner: this is the speed regulator for how long you'd like to keep the green/red lights on. The yellow light control on this particular microchip is regulated by two different modules provided on the circuit board (read about this in the manual included in your kit). Realistically, red/green lights remain on for the same exact time, while the yellow light lasts just a few seconds: it wouldn't make a helluva lot of sense to have each of the three lights lit for the same exact duration (yellow lights are just a few seconds)! Also in the model microchip controller I've purchased, each output port (green, yellow, red) has a maximum amperage rating of 500mA and a maximum voltage output rating of 12-24VDC. That being said, if you copy this schematic, please make sure to choose the specific light bulbs I've used, which are low-voltage LED bulbs with a mere amperage rating of 250mA. Do not use 120VAC bulbs for this particular controller; the company provides an AC version for slightly more money, which can support larger bulbs up to 400 Watts per channel. Again, I chose the DC version so that my traffic light can easily be converted to become portable and run on batteries if need be, also because it's a bit smaller than the AC model, and so that I can use small LED spotlights as opposed to incandescent bulbs. The AC version is recommended for larger projects with bigger bulbs -- and not a traffic light made out of LEGO bricks capable of melting if heated up!
Please be advised when choosing Galak's DC traffic light controller: although the entire circuit board can tolerate a 500mA load, it is intended for model railroads which use tiny LEDs for signal lights -- hence, the pre-assembled model of this controller contains two extra resistors installed to maintain regulated electrical flow to the small LEDs -- which significantly neuters the output power of a larger bulb (LED or incandescent). To get your large bulbs to shine at their true output, you must remove the R24 and R23 resistors from the top and bottom right side of the microchip (see the diagram). Simply remove the two brown/black/red/gold resistors, then short the connection together with a tiny piece of jumper wire, preferably a higher gauge like 22 or 20. If you order the pre-assembled version of the DC traffic controller and leave the two resistors in their place, and then ultimately copy my lamp schematic, your lights will shine dull. The specific lamps I used are over 300 lumen with a mA rating around 280-300, but with the two resistors appear to be significantly less bright -- so dim that the outer transparent LEGO plates will barely shine. If you buy the do-it-yourself kit of this controller from Galak, be sure to omit the R23 and R24 resistors, and instead jumper the two holes (x2) with a thin piece of wire. However, whatever size light you choose for your three lamps, you cannot exceed the voltage/amperage. You must choose bulbs that are no greater than 5 Watts (~ 400mA) and with a voltage that does not exceed 24VDC. Anything greater will simply not light up your project at all, or worse fry the circuits.
Step 3: Tips & Pointers
When using light bulbs, I highly recommend choosing the specific LED spotlights I mentioned in the introduction. If you choose incandescent lights, try to stick with low-wattage Halogen spotlights (MR11) that don't exceed 12 volts nor 5 Watts. When purchasing any sort of light bulb, be sure to adhere to its safety ratings: some LED bulbs cannot be used in timers or relay switches, which means will quickly burnout when used in this project. Do not under any circumstance choose CFL (compact fluorescent light, squiggly energy saving) bulbs for your project! CFLs, even if in low-wattage, are almost always 120VAC, and with their ballast system cannot be cycled through any timers or relays. The LED MR16 spotlights I've chosen are perfect: they're bright, they don't get hot, they're stark white, they can be used with DC projects, they have a low wattage, and most importantly can cycle through a series and blink with timers.
For further electrical safety precautions, please refer to my tutorial for Mosaic LEGO Lamps. In that guide, I give forewarning about overheating your project, handling equipment, and dealing with a live power grid. Since this project I've built is to be plugged into an outlet, be sure to adhere to safety guidelines when using 120V AC power. Never leave your lamp plugged in for extended durations; this whole project serves as a mere novelty to use like a nightlight for a kid's room, or perhaps something cool and quirky to place in your rec-room.
As I've mentioned several times, this is not an easy nor cheap project to build if you're a novice LEGO craftsman! This project was very frustrating and underwent numerous revisions (both technically and ascetically) before finally being photographed. You might encounter some difficulties when building this, and if you've neglected my notations about the resistors in the traffic light controller microchip (step 2), your lights will be rather dull. For the electrical work, refer to my instructions verbatim, but for the LEGO construction, be sure to improvise where applicable and make your own artistic changes. Your finished project can be bigger or smaller, and can even be a different color than just yellow (which is the standard in the U.S.). You can even deviate completely and make a horizontal traffic lamp with the lights going from left to right. However, when deviating, always be certain to have enough space to fit your lights, wires, and microchip without anything getting jammed, and be sure to have the construction sturdy for support.
My grid of colored dots is made in the same fashion of my mosaic LEGO lamps. Having black Technic bricks with transparent pieces may make the output lights seem a bit dull; I built this system with the current design scheme before I completed my Mario lamps and realized that having a certain color brick behind a transparent piece will alter its light color. You're free to have the green, yellow, and red Technic bricks be colored accordingly, so that the green, yellow, and red lights are more true to their desired hue. You can even use my techniques in the Mario lamp tutorial for creating dot patterns, like a green arrow; make sure to plug up the excess Technic brick holes with black LEGO plates.
Step 4: Epilogue
Also special thanks to the jolly good folks at Galak Electronics for their easy-to-use projects, and with their superb tech support whenever I'd run into an engineering obstacle. I certainly recommend checking this place out for some simple electronics kits that you can easily hack/mod.
Super Bright LEDs truly lives up to its name; the light bulbs are of a superior quality, the shipping turnaround times are amazing, and their staff is also very supportive. Definitely turn to them for your bulbs in not only this particular project, but for any LEGO creation that requires bright and low-voltage/wattage light bulbs.
-Baron von Brunk
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