Levitating Lightbulb Does It All With No Wires

It would be really fun to do an entire hallway of these levitating wireless lights. This a project on which [Chris Rieger] has been working for about six months. It uses magnetic levitation and wireless power transfer to create a really neat LED oddity.

Levitation is managed by a permanent magnet on the light assembly and an electromagnetic coil hidden on the other side of the top panel for the enclosure. That coil uses 300 meters of 20 AWG wire. A hall effect sensor is used to provide feedback on the location of the light unit, allowing the current going to the coil to be adjusted in order to keep the light unit stationary. When working correctly this draws about 0.25A at 12V.

Wireless power transfer is facilitated by a single large hoop of wire driven with alternating current at 1 MHz. This part of the system pulls 0.5A at 12V, bringing the whole of the consumption in at around 9 Watts. Not too bad. Check out [Chris’] demo video embedded after the break.

A similar method of coupling levitation with power transfer was used to make this floating globe rotate.

58 thoughts on “Levitating Lightbulb Does It All With No Wires

      1. Having one of these fall on you (full scale size) would probably kill or severely injure you.

        @Elias “Levitation is managed by a permanent magnet on the light assembly and an electromagnetic coil”

        If that coil loses power there’s nothing to hold the permanent magnet in place

  1. I wonder if it would be possible to set up a recovery circuit for power fail situations. Sense power fail, use a supercap to pull the magnet in very close, where it will contact a piece of steel to stick passively. I don’t know if it would be possible to kick the magnet back out to levitate later on, without manual intervention.

    But yeah…I want a hallway of these, build into traditional looking light bulb cases, slowly bobbing while they float.

    1. Should be possible. I have seen many magnetic doors that fail locked. Same concept. Powerful normal magnet, steel plate, electromagnet. The electromagnet creates a strong enough same pole field that the magnet disconnects from the plate. Heaven forbid though you try to open one of those doors without the field … the door will break before the magnet will let free.

      1. Psssst…here’s a little secret:
        Magnetic force is a funny thing, and it weakens pretty quickly. If you wedge a screwdriver near the mag latch and lever it apart even just a little, your 400 lbs of force becomes 40 lbs. From there, a little more wedging becomes 4 lbs.

        Thanks to archimedes, high tech magnetic locks pose little challenge to the average monkey with a screw driver. Most of the world doesn’t know this, but it can save your bacon when you’re locked out of a server room and for some reason aren’t carrying the touch tone generator needed to disable WOPR.

      1. Here’s another thought…

        Could you run the unit so the LED is pointing up? If you could do that then you could put something like a shallow concave plastic mirror on the top and radiate the light indirectly.

        Put the LED assembly in a chrome plastic ball and you’s have something that would look pretty darn cool.

        I hate to trot out the 3D printer thing but this entire assembly (minus the electronics of course) could be printed and then painted and would look awfully professional in the end.

    2. You could just use a small servo or slow cylinoid to push the magnet back into place and then retrackt.

      and ya on power out colaps the field and draw the magnet up with a short birst to a steel or magnetic holder.

    3. I really like this concept :) nice build as well. there’s only one thing left to add to the mix that will make it totally awesome… spinning POV light :D scratch that, two things. we need an EEG cap that turns the light bulb on when someone is thinking too hard :)

  2. I have to wonder how many of these you could hang off the single supply he has there.

    Looking at the scale you could fit this into a simple and fairly small fixture without too much trouble. I highly suggest one in patina’d copper. :-)

    It does bring to mind the question of what kind of electrical noise the wireless power transfer may cause though. I mean what would a bunch of these do to the wireless signal in your house?

      1. I would still worry about harmonics of the 2.4ghz wireless. could still interfere with it. I dont remember which is wors for harmonics, higher or lower… Even RF noise from the rest of the circuit could cause issues with WiFi.

        I have these plastic domes from cameras that i glued togeter and sanded down into clear plastic balls. was trying to think of something to put in them before i glued them together…..this is a possibility :)

      1. From what I can see he’s doing the power transfer from the top not the sides correct? Then making the housing out of copper should make no difference to the power transfer and also cut down on any electrical noise.

        Besides isn’t wireless power transfer just directed RF? If that’s the case it has the same properties as any other signal and can be focused or spread as needed. That means even if he’s doing the power sending from the sides it would be easy enough to make them shallow dishes with emitters in them and put the focal point at the floating location.

  3. I’d been wondering about something like this ever since reading Dune. Good work Chris.

    I’ve been wondering if efficiency of these systems could be improved by having a permanent magnet along with the coil above the levitator. Clearly you need the coil to keep the system stable (Earnshaw’s theorem), but could a permanent magnet do the bulk of the lifting, or am I missing something?

    Another idea is whether a grid of coil magnets could be used in order to move the levitator in the x-y axis? I have grand ideas of someday making a moving levitating solar system.

      1. Yeah that’s what gave me the idea. The need for the cnc though makes it a bit cumbersome. What I’d like is something with no moving parts, that maneuvers the levitator in 3 dimensions by manipulating the magnetic field. Would need multiple electromagnets though.

    1. Actually, when i turn the power off, the floating piece snaps to the wood, the control system turns off quickly, allowing maximum current to flow in the coil and there seems to be just enough residual power left in the power supply to induce enough magnetic force to pull it up. It hangs there because it is itself a magnet and there is a hunk of metal on the other side of the magnet. So making it repel again at start up could be done. Perhaps in v2.0 :P

      1. I actually RTFA and you talk about making kits. Have you thought about kickstarter? Get a nicer finished product together, I’d bet you would make a killing.

  4. I LOVE the idea that when the power fails the lights crash the ground.
    I agree with nimitzbrood about putting LED pointing up and boucing of mirror/white curved reflector to illuminate room.
    I think the falling idea can help to design an interesting light enclosure….

    +1 FTW

  5. I love the idea of using a set of several coils in an X-Y grid in the ceiling, imagine having the light follow you around the room…

    Also agree that it would be neat if the LED was aimed up, that sort of light is much softer, but even with a white ceiling it will draw about twice as much power.

  6. One way to try a do it but would draw more power would be to use on the levitating coil a small magnet which field would be cancelled by the control coil and would react to the power fail by attracting the bulb’s magnet.

  7. If built with as little weight as possible then falling should cause to much injury. If it can be proved to fail safe via magnetic attraction to the ceiling over a year of constant use then I see no reason why this wouldn’t be comercially viable. Scaled up then it would be not to distracting to have the luminaire on a leash! Love it!

  8. instead of a hallway filled with them, have them ftrack you down the hall a step or 2 ahead( sort of a maglev light train) and as for a chandelier, apply same maglev on a circular track with varying height for an epic rotating wireless chandelier =)

  9. neat looking build. A germanium diode array would suckle the airwaves for already present radiowaves to turn into LED glowy goodness. A cap bank and joule thief and viola (hehe) nearly perpetal light after the first day of cap charging.

  10. I’m also concerned about the 1 mHz field put out by the levitator. That’s right in the middle (thereabouts) of the AM radio band. How much would efficiency be compromised by tuning it down or up into less-used RF space? Can it be shielded to mitigate the RFi effects?

  11. Why not encase the whole thing in some sort of clear inflatable ball to prevent accidents in case of a power outage? I’ve seen these “inflatable lamp shades” floating around on the ‘net that seem to be a suitable option.

  12. My idea: replace the LED with a second levitation unit (with a lighter coil, obviously) and hang another floating thing from the first. Then see how long a chain you can make. ;)

  13. A co-worker of mine has a levitating globe on his desk. Permanent magnets make it work, the same setup could be used here. Replace the globe shell with the LED & coil. I like how the light in this moves a little, though, the wobble adds to the ambiance.

    This is a wicked cool build. One in each of the four corners of a room could be fantastic.

    Globe link:

  14. Anyone have any thoughts about the safety of the wireless power transfer if you were to scale this up to hallway-sized. I’ve read that the human-safe level for power density in air is 1 mw/cm^2 (wikipedia).

  15. I would buy a kit for this in a heartbeat…

    But I really suggest you go for a kickstarter to make desk lamp kits for this… or maybe talk to think geek to see if they will fund you for it…

    Too bad it’s on the internet this may have been novel enough for a patent.

    1. also thinkgeek has started their design competition. premise is simple submit a design, if they like it they pay you $1000 for the rights to make it plus 5% of all royalties

  16. as for power failure, must thei “bulb” fall. If i read the various article on the tech right, the electromagnet is used to counter act the attraction of the perminant magnets so that the net magnetic attraction is balanced against gravity. so if the power and the electromagnet fails wouldnt the increase in attraction retract the unit? or is it the same and the electromagnet is an attractive force with perminant repulsion working in concert with gravity.
    Could we not idealy devise a system in which both levatation height and lumen output were both varable?
    On the surface the theory looks simple:
    the electromagnet balances the fight between gravity and perminant magnet attraction. then idealy as the field from the electromagnet goes to zero shouldnt also the distance between magnets? create a large inital field and the attractive field should reduce allowing the object to fall. this of course means free fall but the field would only have to be momentary, pulse with exponental decay, and as the electromagnetic field thins the object would “bounce” as the perminant attraction took over. this should allow enough time for the hail effect to begain balancing the object back into position.

    similarlly, but more difficult would be to apply from the ground up:

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.