DIY Classroom Stoplight (Noise Management Tool)

*This Instructable involves good old fashion wiring. No Arduino or fancy microcontrolers to speak of. So if you're not super tech savvy do not fear. You can build this!

You may have the best organized classroom space out there, beautiful custom labeled bins, Surgically structured cabinets, perfectly parallel pencils, but for me, all that it takes to go from feeling organized and harmonious to chaotic and frustrated is noise. Noise, noise, noise. I don't mean to sound like the Grinch, but any teacher who has been in the classroom for a while knows what a disruptive force noise can be.

Now don't get me wrong, sometimes noise is a great thing, I'm an art teacher and I love it when I walk past my students and hear them energetically discussing their projects or talking about how much fun they're having, but at the same time, I know that too much noise can be a distraction from learning. When it's time to manage the noise I could yell, or clap, or do some sort of call and response activity, but I prefer something less invasive. My stop light sits on the corner of my desk, and when I feel like the noise level is getting out of hand, all I do is flip the switch to yellow or red and my students know to get the noise level under control. I've used this stop light method for the last 3 years, and I have found it to be a great low effort, non intrusive way to manage the noise situation. In my room Green means you can talk quietly to friends at your table, Yellow means whisper talk, and red means no talking, however you could use whatever set of rules best suit your students/classroom/teaching style.

Additionally, even if you're not a teacher a light like this might be a great thing to place outside of your office. Green could mean that you are in your office and open to taking visitors, yellow could mean that you are in, but prefer to not be interrupted, and red could mean that you are out of your office, or that you do not want to be interrupted. (you could even mount this on the wall and drill a hole through the wall so that you could mount the switch inside your office, that way you could change the light without having to open your door while also keeping others from messing with the switch.)

So without further adieu, lets get to it. Check out the following steps for complete instructions on how to build a DIY Classroom Stop Light of your very own.

Step 1: Tools and Materials

You won't need a lot for this project, but some of the items can be a bit tricky to track down. Follow the provided links for easy access to the more difficult to procure items. Total cost will run you right around $40 dollars, If you already have the basic stuff like wood, paint, screws, etc.

Tools

• General Marking and Measuring Tools - Rulers, Tape Measures, Tri Squares, Pencils, and a center punch.
• Hand Drill/Driver
• Phillips Screw Drivers
• Table Saw
• Masking Tape
• Nail Gun - (I use pneumatic nails to hold my stop light together, screws, traditional nails, or even just glue and clamps would work equally well. Use what you have and what you are comfortable with.)

Materials

• Wood - I used some left over 3/4 Oak Plywood and Pine Board. Really any left over wood will work, you certainly won't need much, however, if you want to use the measurements I provide in this Instructable then it is best to stick to stock that is 3/4" thick otherwise you'll need to adjust your measurements.
• Wood Glue (optional for a better bond)
• 4 Position Switch
  
• 24V DC Power Supply (you probably have one of these already, check that drawer in the spare bedroom where you stash all of your old chargers. You'll be cutting the end off of this cord so don't pick one you're going to need later on.
• Industrial Red/Yellow/Green Light
  
• Jump Wires (You'll need some extra lengths of wire to just between positions on the switch. You can source this wire from almost anywhere, just rip apart an old power cord and presto you've got it.
• Paint and Brushes
• Assorted Screws

Step 2: Cut the Wood

After collecting all of the tools and materials for this build, the first step is to head to the table saw and break down your wood into the dimensions found in the above picture. You'll need the following pieces.

Top - 4" X 7"

Top Front - 2 1/2" X 7"

Bottom - 4" X 7"

Bottom Front (Switch Mount) - 5 1/4" X 7"

Left Side - 17 3/4" X 4 3/4"

Right Side - 17 3/4" X 4 3/4"

Middle (Light Mount) 3 1/2" X 7"

*Note that there is also a Back Panel that you will need to cut, however it makes better sense to wait and cut it later on in the build.

Step 3: Cutting Out for the Back Panel (Rabbiting)

We'll be adding a back panel to our light in a later step. Instead of just sticking a panel to the back and having it's exposed edges visible I opted to inset the panel using a technique called rabbiting. Rabbiting refers to the process of cutting a recess into the edge of a piece of wood so that another piece of wood can fit into it. This will allow the back panel of the light to be recessed as opposed to sitting proud. Using my table saw with it's blade set to 1/2" in height, I cut rabbits into to Top, Bottom, and Side pieces of wood as shown in the pictures above.

Step 4: Painting? Already?

With all the parts cut, it's time to paint. Sure you could wait until the end to paint, but trust me, it's easier to do it now before everything is assembled. I decided to go with a black and yellow caution stripe pattern to keep with the industrial feel of the light and switch. To start off I painted everything except the left and right side pieces black, (I opted to keep the side pieces unfinished.) Once the black paint was dry it was time to add the yellow stripes. To keep things as simple as possible I lined up all the pieces and then stretched masking tape across all the pieces at once at a 45 degree angle to make the stripes. After making sure to thoroughly press the tape down to prevent any paint bleed I applied two coats of yellow paint. I find that I get better results when I remove the tape directly after painting (i.e. before the paint is dry) but your mileage may vary.

Step 5: Preparing to Mount the Light

When all the paint is dry, the next step is to drill the hole for threading the wires from the light, and the hole for mounting the switch. In each case I drilled the holes in the center of the boards that these parts are meant to be mounted onto. I used a 3/8" drill bit, but anything up to a half inch would be perfectly fine, the size of the holes doesn't really matter too much.

Step 6: Assembly: Part 1

Next it was time to do a bit of assembly. I started by mounting the bottom front (switch plate) so that it was flush with the bottom and front edges of the side pieces as shown in the picture above. Next I attached the bottom using a 1/2" scrap of 1/2" MDF to raise it up slightly so that when finished the stop light will stand on the bottom edges of the side pieces and not on the bottom piece, (in my experience big flat bottoms on projects tend to make them more prone to tipping or wobbling on uneven surfaces.)

Step 7: More Hole Drilling

Time to drill the holes for the switch. There are 5 in total, one main hole for the switch shank to pass through and 4 auxiliary holes for mounting screws. Start with the main hole, using a 3/8" drill bit drill right in the center of the bottom front piece (5 1/4" X 7"). Once that hole is drilled disassembly your switch by removing the knob and cover plate as shown, and then use the switches' mounting plate to align and mark for the 4 mounting screws.

*So... I made a mistake and it's worth point out so that you can plan around an issue that I didn't see coming. The screws that come with the switch for mounting it aren't long enough to extend through the 3/4" wood that I used for this project. There is an easy and a hard solution to this problem. Easy solution, when you buy your supplies, pick up some longer screws. Hard solution, buy a house that is 45 minutes from the nearest hardware store, realize you don't have any extra long screws, decide to chuck a router bit in your drill press and slowly route away wood from the back side of the switch mounting board until it is thin enough that you can use the original screws. Guess which solution I went with...

Step 8: Assembly: Part 2

At this point there is really nothing holding you back from putting the rest of the light together. The reason I decided to wait until this point to assemble everything is because I thought it might be a bit tricky to drive the screws that hold the light to it's wooden base if everything was assembled first. However, since we've already attached the light, it's a non issue, so go ahead and finish putting everything together just as shown in the pictures.

Step 9: Time to Build the Back Panel

Okay, finally time to build that back panel. I waited until this point in the build because little changes along the way, like raising the bottom of the stop light changed the over all dimension of the opening in the back of the stop light. My back panel ended up being 8" X 16 3/4", however I suggest you take your own measurement at this point to ensure a nice fit.

Once I had cut the back panel I gave it a few coats of metallic silver paint. My thought process here was that I wanted something that would reflect light, thereby making the light appear brighter.

After painting I drilled a small hole near the bottom center of the panel. This hole allows access for the 24V DC power supply.

*Tip - Go ahead and put the cord for the 24V DC Power supply into that hole RIGHT NOW. I forgot to do this and accidentally wired the entire light without putting the 24V DC power supply through the hole and then I had to take things apart to fix my mistake. Stick that cord through the hole and tie a knot it in for good measure. (Tying a knot in the cord once it's through the back panel also protects against accidentally pulling your wires out of place if the light would fall while plugged in. The knot in the cord will bind against the back panel of the light keeping slack in the wiring where it attaches to the switch). Look at that, you got two tips for the price of one.

Step 10: Wiring (This Is the Hardest Part)

So this was the trickiest part of the project for me, so many wires, so many different combinations of wires and switch positions, and so so many ways to put things together wrong. Eventually I figured it out and I've included helpful pictures for you so that you won't have to play the wire trial and error game like I did.

Here is what you need to know, The Red, Yellow, and Green wires are all correctly color coded to the light colors, (so nice, the manufacturer could have just as easily made them all grey.) The grey wire is your neutral. The blue wires are jumper wires that I stole from one of my sons broken toys. The black wires are the positive and neutral from the 24V DC Wall Adapter.

Now for the Switch, It has 8 ports in total for us to potentially connect wires into. We will be using ports 1-6. Thankfully all the ports are numbered to make life just a little easier.

Port 1 - Insert the positive end of the 24V DC power supply and 1 of the blue jump wires.

Port 2 - Insert Green Wire.

Port 3 - Insert the other end of the jump wire in port 1 and one end of the second jump wire.

Port 4 - Insert Yellow Wire.

Port 5 - Insert the end of the second jump wire.

Port 6 - Insert Red Wire.

Lastly, Connect the Grey Neutral from the light to the neutral from the 24V DC Power Supply. Tighten all connections with your screwdriver, and use either heat shrink tubing or electrical tape to cover any exposed electrical connections. Once everything is safe, plug your light in and turn your switch to position 1, you should see a green light come on. At position 2 you should see yellow, and at position 3 you should see red. At position zero the light should be off. If all of that happened, then congratulations you successfully wired your light!!

Step 11: Finishing Things Up

With everything working properly, the light is almost finished. If you haven't already done so, mount the switch onto the bottom front panel. Next carefully tuck your wires away and set your back panel in place. Use 2 or 3 nails to attach it (In the event that you need to dismantle your light, you should be able to easily overcome the holding force of those nails allowing for quick access to the internal electronics.)

Plug the light in again and check to make sure everything is still working correctly, if so then congratulations you just completed your DIY Classroom Stop Light!

Thanks for following along with this project. I hope you learned a few things along the way, and maybe even made a stop light of your own. Please feel free to share your thoughts and opinions in the comment section.

Step 12: