Shake Generator





Introduction: Shake Generator

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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)
  • Materials:
    • 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
  • Tools:
    • Soldering iron / solder
    • Sandpaper
    • Wire Cutters

L-L-L-L-E-E-E-E-E-E-T-T-T-S-S-S-S Shake!

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. :)



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    31 Discussions

    No, I did not assemble it. By increasing the turns, you induce more voltage. You need to induce more than the forward bias voltage of the LED to see a blink.

    I could put this on my bicycle actually, I 'll generate light all the time since the bicycle roads are a bit in a bad state here :D

    2 replies

    A lovely point! And yes to BrianM172, one magnet on the wheel itself whizzing by a coil or visa versa will give you a generator indeed. :)

    No need to think about bumpy roads... the rotation itself is enough to generate electricity. If you add more magnets, then it makes more light overall, so just do that


    2 years ago

    First, you will get more efficiency out of it by learning to coil. A hap-hazard coil like that *will* work, however a structured, clean coil will work better. Increasing the length of time the coil is in the magnetic field will increase the electrical output potential. Adding additional layers to the coil (in one of various ways) will increase time of coil saturation in the field as well. Of course, a stronger field will also work to increase electrical output, however the coils are the more important to *no pun intended* straighten out. The shape and size, as well as the strength of the magnetic field are also important to this type of electrical production. It is the interaction of the leading and trailing edges of the magnetic fields to the coiled wire which causes the protons in the wire to excite.

    With this said, it would be best to have the coil would at least 1/4 of the length of the pipe, preferably taped off between layers, with multiple layers of coil. The wire should go straight back to the starting end of the pipe to begin each subsequent layer, with paper or rubber tape (or if you want to get real fancy, enamel paint (like fingernail polish)) to separate the coils from each other as well as the straight lengths from each coil. Ideally the magnet would have a doughnut shaped magnetic field where the thickest part would traverse the coils.

    So far, this is sort of what you've done (and a couple things to correct what could be done better with what you have already) Now for some even more cool stuff:

    Adding three thin, low-friction rods into the pipe around the magnet would keep it centered without adding resistance (and possibly decreasing it). A spring at each end would cushion the magnets sudden stop (which is being done with the cork now) but also add mechanical energy back into the magnet for the return direction. This would make operating slightly easier.

    Adding several capacitors in-line with the LEDs will contribute to a more stable light, though will require a charge up time. Add enough capacitance and the LEDs will remain on for extended periods. Combining three of these into a single circuit, stuffed into a larger pipe with capacitors could be used to create a handy flashlight... and also probably shouldn't be taken any where near a TSA officer. >_>

    In theory it would be possible to wrap a coil around a pipe from end to end, and bend the pipe around, with (a) magnet(s) inside that would continually traverse the length of the tube. (Think Hula-hoop) Which if the magnets could be kept in motion relative to the loop, such as on a bicycle tire, where mechanical energy is already being spent, this could act as a way to electrically power components not suitable for hard wire, and where on/off switches are not necessary due to the natural resting off position of the circuit.

    (If you're going to do the hula-hoop thing, may I suggest cutting the tube in some spiral form so as not to have and edges which would catch the magnet's edge, and would also be more structurally sound after repairing, and would allow the use of the wire coils to add strength to the repair)

    And now you're asking "Why don't you just do it and make an instructable?" - because, well, building the hope that some one else could learn from my ideas and thoughts, and possibly create the next globally profound thing, is in itself absolutely exhilarating! Also, I've done these things and have moved on to other things, also I don't think about taking pictures and video when working on things until I'm done >_<

    2 replies

    Hey Aesix!

    This is a wonderful and very in-depth look into generator efficiency, and I love it. It's a great way to expand the project beyond demonstration demonstrating basic electromagnetic properties. It would be neat to challenge students to come up with ways to increase efficiency, and see how some of the concepts you discuss emerge.

    Thank you again!

    For bold, you gotta press CNTRL+B, or highlight text and select from there, as *text* does not work

    it's all about bobine basics and tesla théorème but it's realy a good idea keep going :) ;)

    Hm... if you think, this is a VERY cheap project. You need about 3.4 volts to light an LED, but if you follow suggestions that were listed below, you can make the pipe thinner to increase the output, (creds to SajalB1) you can get a LOT more than 3.4 volts. However, it only costs about $5.00 to make one, and a TON less if you're conservative... Then make a wheel that runs on magnets pushing off each other (Look on youtube) then connect many rods to the wheel, and as it spins, the contraption should give off a TON of power, probably even enough to light a regular, fluorescent light bulb.

    2 replies


    "Then make a wheel that runs on magnets pushing off each other (Look on youtube)"

    This is just a BIG fake because this is impossible in physic.
    Ask to Newton ! Or just loose your time to test this... ;)

    Nope its possible. Honestly I admit that the magnet wheel is a bit too much, but there is a wheel that has rods that when they fall, they make enough momentum to keep the wheel spinning. its called "overbalancing"

    i would-be have used only the red ones,( they need the minust less voltage. Blue is almost the highest,thats why that one almost never wil go on... But verry cool

    I am going to make one also.

    With a 1/2 inch pvc pipe, how long would the wire have to be to have a electrical current?

    The lighting effect would be much more intuitive if you attach the LEDs to the "shaker" with a relatively long wire, so they can remain stationary (on a table) while you shake your booty.


    2 years ago

    This is a great looking project! I really must give this a try.

    One thought - you might find that a "joule thief" type circuit would help the LEDs to light - it would probably only work in one direction (maybe you could use two opposing circuits) but I have found with other manual generators that this type of circuit will light up an LED with much less effort than simply connecting it to the generator output.

    If I remember, I'll try it and let you know.