Kaiden finally received his long-awaited Lego Star Wars Millennium Falcon from Santa. By the next day, all 1,254 pieces were assembled. Pretty good for a 5 year old who stopped to play while he was building.
As we flew the ship around the living room one evening, the blue Christmas tree lights gave me the idea to install some LEDs in the back of the Falcon to light up the hyperdrive. I remembered that I had some small, bright blue LEDs left over from a robot project and we got straight to work. Below is a walk-through of what we did as well as a few alternative options to consider if you plan to do this yourself.
Stuff You Need
You may not need all of these tools and parts, but here’s what we used:
- Wire cutter
- Wire stripper (optional, but I love my wire stripper)
- Crimping tool
- Soldering iron and solder (you can get cheaper ones, I’ve had this Weller for many years)
- Helping hands (mini-vise to hold parts while soldering)
- Rotary tool (if you need to modify the Lego parts, my 20 year old Dremel still works like a charm)
- 4×LEDs (bright blue or white)
- 4×2032 3V coin cell batteries
- momentary push-button switch (or a toggle switch if your 5 year old always remember to turn it off… yeah, right.)
- 6×2-pin header connectors (see picture)
- 1×4-pin header connector
- 4×male header pins
- 12×female header pins
Notes on header connectors and pins:
- You could do without the headers and pins and crimping and just solder wires and LEDs which would be much quicker. I like to build things so that I can re-use the parts later when (not if) my son finds something more interesting. My Railroad Crossing Signal is a good example and we’ll be leveraging the sound chip from that for some sound effects in the Falcon later!
- You can buy 100 of each type of pin quickly with Amazon prime (male, female), spend 10× less on eBay (male, female), or buy a smaller quantities of connectors and pins at places like Futurlec. If you have a local electronics store, like Jameco or Anchor, please support them!)
- I modified a couple of parts, but there a million options for securing buttons, LEDs, and batteries since it’s Lego!
How We Did It
- Decide on a layout. Choose whether you want the LEDs in parallel or in series. This determines what your battery pack looks like as well as whether the entire things stops working if one LED bites the dust (series). The blue LEDs have a typical forward voltage of 3.5V so to keep everything simple, I used 4 3V coin cell batteries in series with 4 LEDs. So the circuit is very simple.
You also need to decide how to connect the various components. Based on the ease of making a small, square battery box and the use of header connectors which let us easily replace individual LEDs, we went with the serial option. If you solder parts instead of using connectors, consider how you’ll make repairs. This is also a good time to disassemble the back of the ship and identify where everything will go.
- Build the battery box. Kaiden designed the box out of Lego parts and we adjusted the height to fit 4 coin cell batteries with just a little space remaining. The parts shown include decorative pieces at the top of the picture.
Click here for a video on assembling the battery box:
To attach leads to the battery, I just used the same 22 gauge wire, stripped off extra insulation, and created my own springs. Once the top panel of the battery box was closed, it created a tight connection that has not come loose since.
- Crimp or solder the wiring. Measure wire lengths based on your decisions in the first step. You might consider soldering components or using fewer connectors, for example, on the battery pack and switch. The reason I put connectors on those parts is because I thought I might later add a microcontroller to flash the lights. I also have quite a few of these connectors in my parts box. Here’s my schematic with the connectors shown.
Here is good video tutorial on crimping if you’ve never done it before. The video covers more than just one type of connector and pin and shows how easy it really is.
- Prepare the button. I used a single 2×2 brick to house a push button that could be easily attached to the underside of the ship and that worked out nicely. Choose a brick to match your button or switch or find another place to mount it. I had to drill out the middle of the brick a little so that the button would be flush with the edge. I also drilled a small hole in the side for the wire connecting the switch to the rest of the circuit. The momentary push button also ensures that none of us will forget to turn off the lights when we are docked at the space port at dinner time.
Cut or drill out some of the block so the switch fits inside and also drill a small hole for your wires to go through.
- Install the LEDs. We needed another “custom” Lego part to hold the 2 LEDs in the middle in place. It may be an actual Lego part, but we didn’t have one so I found a Technics piece that I could just cut in half.
These pieces are used to hold the 2 LEDs in the middle in place like this:
A little more disassembling might be in order…
The 3mm LEDs fit nicely inside the blue tubes and here is how we assembled these.
We ended up having wires strewn about the ship, but if I recall, the Falcon was a bit messy inside anyway so we won’t waste time trying to hide any wires.
I may change the configuration later when we add more lights, but for now, it’s a nice, simple and cheap setup. The next logical addition is to add forward flood lights so stay tuned.