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I am trying to understand on a high level, how famous floating light bulb actually works.

https://www.floately.com/products/volta-light-bulb

I kind of understand how it floats and how it is supplies power to the bulb via electromagnetic induction.

But what I don't understand is how it rotates and how you are able to power it on and off.

From what I can understand two magnets repelling each other creates the levitation, however what I don't understand is that how you can control its movement. How is this done ? I have no clue about this.

Also, how do you toggle the light on/off ?

ChatGPT seems to suggest you can put something like a infrared transmitter at the top of the platform where the light floats, and a receiver at the base of bulb, then send signals to it. Is this feasible ? I don't think so because the power sent to the bulb doesn't seem like it would be able to support this.

ng.newbie
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    You can rotate it by generating a rotating magnetic field in the base, and the bulb itself has a set of magnets that are interacting with it. Alternatively, I am not sure it is the case, but it could be just that it is rotated manually and with very low friction it will spin for a long time. w.r.t/ "Also, how do you toggle the light on/off ?" - what is the problem? You just switch the part of the circuit responsible for the power delivery off/on. – Eugene Sh. Jun 23 '23 at 19:59

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Based on nothing but what is on the linked page. . .

To move energy across an air gap you need an alternating current. The power supply probably is a wall-wart, with an oscillator and power amplifier are in the base unit, and it has a clearly marked on/off switch location. This could be a membrane switch or a capacitive touch switch circuit, but either way that covers the power and control parts.

The light can be turned off but still levitate, so there might be a very low power wireless data link between the base and the bulb. With a $1 microcontroller, a ton of things are possible.

There is a wire coil in the light bulb base that acts as the secondary of an air-core transformer. Depending on the LED string construction, either the AC waveform is applied directly to the LED strings (with strings mounted in opposite-conducting directions), or rectified and applied to the strings with all strings conducting in the same direction. Either way, the strings are flickering too fast for the eye to perceive.

In the video, lights are rotating in both directions. This suggests that there is nothing guiding the bulb's motion.

The text implies that the levitation and power transmission are done with separate systems. Here is what I hope they are doing:

The drawing shows four electromagnets in the base. There also could be neodymium magnets in the base and bulb to help with levitation, but the main levitation probably is produced by an aluminum disc in the light bulb base. The AC field induces eddy currents in the disc, and those currents produce their own field that opposes the base's field. This is captured by a minus sign in Faraday's Law of Induction.

Something like this:

https://www.youtube.com/watch?v=AHED5xSnnM8

https://www.youtube.com/watch?v=A7BScXvM8w0

OTOH, the levitation could be done 100% with permanent magnets, and the electromagnets are used for power transmission only. If so, this makes power control very simple; turn up the output of the power amplifier, bulb gets brighter. Turn the power amplifier down or off, and the brightness goes down or off. No brains needed in the bulb base.

AnalogKid
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  • I really like your answer, but is the movement done via a rotating magnetic field as suggested by Eugene's comment ? – ng.newbie Jun 24 '23 at 18:10