Introduction: Child's Toy Light Switch Box

By YouTube
About: Writer for Science Buddies (www.sciencebuddies.org) and lecturer at Cornell University's Sibley School of Mechanical and Aerospace Engineering.

The inspiration for this project came from babysitting my 1-year old nephew. He will quickly lose interest in a room full of toys, but he LOVES light switches. The problem with light switches is that they are several feet off the ground. This requires an adult to stand there holding him so he can play with the switch. Typically, the adult's patience for this will run out long before his does. So I thought of a solution: light switches that he can reach, in the form of a toy box with light switches and LEDs. Simple to make for about $25 worth of parts, it was a fun afternoon project and well worth it based on his reaction. If you're a little intimidated by the awesome NASA mission control desk, but would like to learn how to make such panel-based toys, this could be a good way to start! If you get stuck or have any questions, please leave a comment and I'll get back to you as soon as I can.

Head on to the next step for a materials list. But first, check out this video of the finished device in action:

Step 1: Materials

I got the most of the hardware for this project in-person at Lowe's:

You will need the following circuit components - this is all standard stuff you should be able to find at your vendor of choice (SparkFun, Adafruit, Radio Shack, Jameco etc.) or may already have laying around if you have a well-stocked workshop (note: I forgot to include a couple of these in the picture above):

You will need something to actually make the box. I got the wooden box pictured above from A.C. Moore for $6. Some other suggestions:

  • Cardboard box (shoebox would work well, but may be less durable in the long run)
  • Large tupperware container or plastic storage bin (cool because you can see the wiring on the inside)
  • Build your own box from scratch (I was in a hurry so didn't take this route)

Finally, you will need the following tools (this may change depending on what material you use for the box):

  • Phillips and flat heat screwdrivers
  • Power drill with assorted bits
  • Jigsaw
  • Soldering iron
  • Wire strippers
  • Hot glue gun
  • Heat gun or hair dryer if you're using heat shrink tubing
  • Ruler
  • pencil

* Value does not have to be exact - I picked a small resistor to go with
the 3V battery pack, but didn't actually bother doing the LED current calculation.

Step 2: Design the Front Panel Layout

The front panel layout is up to you. You mainly need to decide two things:

  • Where to drill holes for the LEDs
  • Where to cut rectangular holes for the electrical boxes

I went for a simple approach with the light switches side-by-side and the LEDs centered above the four switches. No fancy CAD work here - above you can just see a sketch of my layout with dimensions (although, gee, it sure would be nice if I had my own laser cutter to make a fancier front panel...).

Note that the holes for the electrical boxes are smaller than the perimeters of the faceplates. The second image above shows this. Also note that the electrical boxes each have six tabs around the perimeter - you do not want to include these tabs in the outline that you cut in the front panel. You just want to cut a rectangular hole, so the box can slide into it, and the tabs will rest on the surface of the front panel (see "side view" diagram).

Once you've come up with your design, use a pencil and ruler to trace it onto your front panel.

Step 3: Cut the Front Panel

Now, cut out the rectangular holes for the electrical boxes, and drill holes for the LEDs. Again, the tools and methods you use to do this might vary depending on the type of box you're using. I drilled four pilot holes in the corners of each rectangle, then used a jigsaw to cut out the rectangles.

Next, I picked a drill bit with a diameter wider than the spacing of the LED leads, but smaller than the outer diameter of the LED. This will allow me to push the leads through the holes, and have the bottom surface of the LED flush with the front panel.

Step 4: Attach Wires to the Switches

Important safety note before you continue: DO NOT FOLLOW THESE DIRECTIONS TO INSTALL REAL LIGHT SWITCHES. This is a battery-powered, low-voltage hobby project.Light switches in buildings are hooked up to high-voltage AC, which can either kill you on the spot if you don't know what you're doing, or burn your house down later if you do a shoddy job with the wiring. I am not a trained electrician, and I have zero experience with light switch hardware before doing this project, so I made this up as I went along. If you need to install real light switches, contact a licensed electrician.

Anyway:

  1. Cut 8 segments of hookup wire. I'd recommend doing 4 segments each of 2 different colors. The exact length you need will depend on the size of the box you're using and your front panel layout - I'd recommend starting with about 12", and you can always trim them down later.

  2. Strip the ends of the wires.

  3. Each switch should have two screw terminals on one side (there is a
    third screw on the opposite side, but you can ignore that). Wrap the end of a wire around each screw, and use a Phillips screwdriver to tighten it, as pictured above.

  4. Do this for all four switches.

Step 5: Mount the Switches in the Electrical Boxes

Lots of pictures for this step! Time to mount the switches in the electrical boxes.

  1. Pop out the little circle on the back of the electrical box (I used a hobby knife to weaken the tabs holding it in place).
  2. Thread the wires you attached to the switch in the previous step through the hole.
  3. Pull the wires through to the back of the box.
  4. Align the switch so it is resting on the front of the box. Mounting holes on the switch should line up with holes in the box.
  5. Use the screws that came with the switch to attach it to the box.
  6. Repeat steps 2-5 for the second switch, so you have four wires sticking out of the back.
  7. Repeat steps 1-6 for the second electrical box and the other two switches.

Step 6: Mount the Electrical Boxes on the Front Panel

Mount the electrical boxes to the front panel:

  1. Slide the boxes into the rectangular holes.
  2. Each box has two screws in diagonally opposite corners. Tightening these screws pulls up a tab on the back, clamping the box to the front panel (see pictures).
  3. Fully tighten all four screws to secure both boxes to the front panel.

Step 7: Mount the Faceplates

This one is pretty simple - each faceplate should have come with four screws. The holes in the faceplates will line up with holes in the switches, not the electrical boxes. Use those screws to secure the faceplates.

Step 8: Mount the LEDs

This is where the glue comes in (fingers crossed for the glue contest). Either put glue on the back of the LEDs, or around the perimeter of the hole on the front panel, then thread the LED's leads through the hole and press it firmly against the front panel. Just be careful not to get glue all over the place, since you'll have to clean it up later (including the LED's leads, since you'll need to solder to those).

Important: pay attention to LED polarity! To make things easier in the next step, I'd recommend having all the long leads (anode) and short leads (cathode) aligned. Although it's hard to see in the last row above, all my long leads are facing to the right, and all the short leads are facing to the left.

Note to parents - my LED leads are corroded because I'd previously used them with Squishy Circuits and was lazy about cleaning them off. If your kids are the right age for you to actually read this far, they'll probably have fun with squishy circuits too.

Step 9: Wire the Circuit

I was in a hurry to get this done while my nephew was visiting, so I did a pretty bad job with cable management - I apologize for the messy pictures. If you're familiar with circuit diagrams or "breadboard diagrams" (even though there is no actual breadboard involved here), you can probably just follow one of the first two diagrams above to wire the circuit. Otherwise, you can follow these steps:

  1. Remember, if you are using heat shrink tubing, to slide it onto the wires BEFORE you solder them together. Not that I have ever made that mistake.
  2. Solder the red (positive) lead from the battery pack to one terminal of the rocker switch.
  3. Twist the leads of the resistors to the long* leads of the LEDs and solder them together.
  4. Use hookup wire (I'd recommend red, if you have multiple colors) to solder each resistor to the other terminal of the rocker switch.
  5. Solder one wire from each switch to the short lead of its corresponding LED.
  6. Twist together and solder the other four wires from each switch.
  7. Solder those wires to the black (ground) lead from the battery pack.
  8. Mount the battery pack and rocker switch inside the front panel using hot glue.

If you need more help with this step, here are some good references:

* Each individual LED is wired in series with a resistor and a switch. The order the three components are in doesn't really matter, this just happens to be what I picked.

Step 10: Test the Front Panel

You probably want to make sure this works, otherwise you might have a very disappointed toddler on your hands. Make sure the internal rocker switch is on, and flip each light switch back and forth a few times to make sure the LEDs turn on and off. If nothing explodes or breaks, and you don't see any smoke, odds are you're good to go. If the LEDs don't light up at all, the mostly likely cause is probably just that you have their polarity backwards. Double-check that and the rest of your wiring and solder connections, then try again.

Step 11: Optional: Finishing Touches

Obviously how you choose to decorate the box, if at all, is up to you. I chose to just keep a minimalist approach and not do any painting. I did sand down the edges and corners slightly because they were a little sharp, but that's it.

Depending on the type of container you used, you might want to add some sort of hinge or latch mechanism, to prevent a curious kid from taking off the lid and ripping out the wiring.

Step 12: Play Time!

Time for some audience testing! My nephew was a little confused at first and tried pushing the LEDs. Once we demonstrated the toggle switches, he was quite happy to sit there flipping them back and forth. He seems to like the green LED best for some reason.

So of course, he'll outgrow this eventually...but that will give me an excuse to build one of those mission control desks.

Thanks for reading! If you have any questions, please don't hesitate to ask in the comments below.

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