For the past couple of years, Digi-Key has been inviting schools from our local and surrounding communities into our facility to provide them with a valuable, educational experience. We’ve always offered tours of our facility when they have been requested, but to increase the quality of their time with us, we started also providing hands-on projects or demonstrations with some of our more fun technologies.
In this time of uncertainty, we would like to present the details for a few projects to help entertain your little ones, while helping them grasp some simple STEM concepts. For each project, we will try to give examples of household items that could be used in place of the electrical components used in the original instructions.
First up: Operation STEM
This is a simple, fun take on the popular household game. It will teach the concept of a switch and how to complete a circuit.
What you’ll need:
*Length of wire is dependent on the size of the enclosure used.
**The smaller the enclosure, the less wire you’ll need.
First, take the bare wire and make some sort of form with it that will fit on the top of the enclosure being used. Keep in mind that it cannot be touching itself anywhere and that you’ll want there to be some tolerance to more easily run the other wire along it when the game is finished. Figure 1 is an example of one wire form that was created for this project. Please set this form off to the side for now, somewhere out of the way so it will not lose the desired shape.
Figure 1: Wire form.
Now, take the enclosure and, using something with a diameter no larger than the tip of a ballpoint pen, poke two holes in the top on opposite sides (Figure 2, Stars 1 and 2). This is where you will place each end of the wire form you just made later in this guide. Then place one more, centered between the first two but as far out (away) from them as your enclosure allows (Figure 2, Star 3). This is where the looped wand wire will be placed. See Figure 2.
Figure 2: Hole locations for wire to be run.
Let’s make some connections and mount all the other pieces in place. Start by connecting the battery’s negative terminal (black wire if you’re using a battery pack) to the negative terminal of the bulb or speaker. If these items both have wire leads, and you have wire nuts that are the proper size, adhere them with the wire nuts. Otherwise, go ahead and make the connections using electrical tape and insulated wire.
Whether using a wire nut or electrical tape for the connections, strip a small amount of insulation off the end of the wires to be connected, then, holding them with the stripped ends lined up, twist the ends around each other, and place the wire nut or tape.
Tech Tip: If using a screw-in type bulb, the negative portion is the threaded part, while the positive terminal is the button on the bottom. If using a speaker with leads, typically a black lead will indicate the negative terminal while a red lead will indicate the positive. If you happen to have a through-hole LED lying around, the short lead (often accompanied by a flat side on the lens) is the negative lead. If you have found any other item to use as an indicator that you are unsure of the polarity, just give it a quick Google search.
Next, connect the positive terminal from your light or speaker to the insulated wire that will be used as the looped wand wire. Now it’s time to start placing items in the enclosure. Take the insulated wand wire and press it through the bottom of the enclosure so that it comes out of the top of hole 3 that you made earlier. Then use electrical tape to adhere the batteries within the enclosure, along with the speaker. If you are using a bulb, you’ll want that visible from the outside of the enclosure. Figure 3 shows the wand wire coming through the inside/bottom of the enclosure and connected to the positive terminal of the speaker we used via a wire nut. Again this connection could be made with wire and electrical tape if there are no leads on the speaker or light being used.
Figure 3: Wand connection.
Now is a good time to place the wire form. Insert the two ends from the top side of your enclosure through the two holes we poked earlier. Then take the one closest to the positive (red) lead of the battery and use a wire nut or electrical tape to connect them. Secure that connection to the inside of the enclosure using electrical tape. This will help to protect the connections and hold everything in place. Grab the other end of the wire form that is already pushed through to the inside of the enclosure, and bend the lead enough to secure it from pulling back out, then tape it down.
At this point, all of the proper connections should be made. To test and see if it’s working, take the insulated wand wire, strip about 2 inches of insulation off the disconnected, free end and create a hook that is not pinched tight - you need to be able to loop it onto the wire form design. Then place the loop on the wire form and try to maneuver over the entire form without touching the metal from the wand to the metal of the wire form. If you do, it should trigger the speaker or light or whatever other component your craftiness found!
If everything works, great job! You’ve created a family-friendly game to enjoy. If it doesn’t, don’t panic! Especially when using electrical tape for the connections it can be easy for one to come loose. Just recheck all of the connections, make sure the batteries are in the proper orientation, and test it again. Good luck, and remember to post a picture of this on social media using the #MakeWithDigikey so we can see your version of Operation STEM!
Figure 4: Completed project.