This takes some shake to make!
Time to make some light with the original shake weight, the piston generator. No batteries needed! Just some good old fashioned human power. This is one of my favorites for an introduction to electro-magnetism, and works great in concert with showing that electricity can make a magnet. Now you know it works the other way, too.
- What: Shake Generator
- Concepts: electromagnetism, polarity, electronics, motors
- Time: ~ 20-30 minutes
- Cost: ~ $1 (all reusable)
- PVC (1/2" works well)
- Magnet wire (thin wire)
- Magnets (one or more, small enough to fit in PVC but similar radius)
- LEDs (low power diffuse works more easily)
- Corks x 2
- Soldering iron / solder
- Wire Cutters
Step 1: Wrap It!
Let's get into the loop. Several hundred of them.
Start out with your wire wrapped around the PVC tube near the end. Hold down with your finger while you wrap it a few times to make the end secure, leaving a little room for the end to poke out. Then it's a great time for a conversation, to watch a sitcom, or get a dental exam, because you're going to wrap a couple hundred times. Don't worry, it doesn't actually take that long. :)
Snip the end of the wire, and pull it around so that both ends are on the same end of the PVC pipe. Sound both the ends to remove the coating so you see exposed silver color.
Coils are key to a lot of electromagnetism. As a magnetic field passes near conductive wire, it creates a small amount of charge in a given direction, but it's very very tiny. Only with a hefty amount of wire in the same orientation are we able to get enough voltage to power most electronic devices.
Step 2: When Two LEDs Become One
What a pair!
Take a look at your diffuse LEDs, and note that the legs on a given LED are different lengths. The longer one is the anode (+) and the shorter one is the cathode (-). Line them up and solder them such that the anode of one is touching the cathode of the other. Or rather, the long leg of one is touching the short leg of the other.
This is taking advantage of the polarity of LEDs. LEDs only work with electricity passing in one direction, and so each direction of electricity will turn on just one of the LEDs.
Solder the connections for a firm hold before we start shaking it.
Step 3: Solder to Your Wire
Take the two pairs of legs, and solder one to each end of the wire where the insulation has been stripped away. The orientation of this solder isn't as important because no matter the direction of the magnetic field, one LED will be lit.
Slide your loops and LEDs to the middle of your tube and secure it with a little tape. The reason for being in the middle is the magnet should be traveling fast enough to generate the needed amount of light.
Step 4: Magnets in the Chamber
Put your magnet or magnets into the tube, and get ready to rock. You can close the ends however you choose, but I've found cork that can fit inside the PVC to be good for a little springiness, soft noises, and durability.
Step 5: Make LIGHT!
Shake to make! Slide the tube back and forth making the magnet slug move back and forth through the tube. As you go faster and faster, you'll notice the LEDs starting to light up one at a time. You're making that!
Here are some things to think about and experiment with:
- What happens if you change the diameter of the tube?
- What about increasing to two magnets? Or more?
- What happens with more coils?
- Or different LEDs?
- Do you notice which LED turns on more often? (the red) Why do you think that is? How could you test that?
Move some magnets, make some light, and as always, keep exploring. :)