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I want to know if anyone knows a way to do this at home. Acoustic levitation is a way to levitate objects in space using sound waves. That site gave a very thorough explanation of how it works, but not how to do it. If someone knows how, I'd love to see an instructable.

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## 24 Replies

Yonatan24 (author)2017-02-10

I'd like to just clarify a few things I've read here. Firstly, the diagrams that seem to illustrate a "figure 8" with the particle in the loop assumes you already have a notion of how sound actually works. Sound doesn't truly travel through air as a vibration travels down a string (with an "S" shape), like these diagrams illustrate. Sound is a longitudinal wave. It is a compression of air travelling away from the speaker. The sin wave diagrams that you see all the time describing sound traveling through space just illustrate at what distance from the source you'd find high pressure and low pressure (curved) planes. So in the diagram, when it shows the particle suspended in a loop, this really means the particle is suspended in a low pressure plane sandwiched between two planes of higher pressure. Naturally, things like to be pushed away from higher pressure towards lower pressure. Thus levitation.

Another point, it has been mentioned multiple times that the wave needs to be quite strong to produce significant levitation, bit that doesn't necessarily mean you need a huge amplifier and specially made speakers. If you generate a standing wave, by definition, you are achieving resonance. At resonance, a wave can be greatly amplified. This would lower the actual amount of power you need to be pumping into the air. I haven't looked into the details here, so maybe these figures already took that into account, but given that someone mentioned they were able to do it with their voice, i don't think you need 150 DBs for a small object. Furthermore, the object geometry should come into play. If you had a very light object with a relatively large surface area perpendicular to the wave (a small piece of paper) i would imagine that you wouldn't need as much pressure.

Also, this guy seems to have done it with a small device:

https://www.instructables.com/id/Acoustic-Tractor-Beam/

JeffreyB43 (author)2016-03-22

Sound waves are not waves as you normally think... like little lines of wiggly waves... there are in fact little spheres...so there's much more to this than you imagine. For further insight, google: john stuart reid - photographing sound, and from there follow your next instincts with regards to researching "how to levitate objects"

Sandisk1duo (author)2009-01-02

umm, i don't recommend you do this, you will probably kill yourself, you need a bunch of power, speakers that go up to 600khz at 155db+

bottom line: don't even attempt this

stormclaypoole (author)2014-09-19

It is pathetic and ignorant to think the way you do. It is possible without electricity, let alone your jumbo speakers. Now, on the other hand he could kill himself by attempting to break apart and move a megalithic slab. Bottom line: Everyone should attempt the unfathomable depths of ancient (or I suppose to someone like you, future) technology. We can create a much better world using energy and vibration. Trial and error is a key.

Koin444 (author)2013-03-22

This isn't necessarily true in all cases. I have done a demonstration for my family using my voice and a small square of flat paper on a smooth flat surface. In order to lift the paper you need to hit the correct vocal pitch. At first I thought it was my breath but after doing the experiment multiple times using various pitches and breath patterns and force I concluded the resulting lift to truly be an inexpensive legitimate demonstration of Acoustic levitation. Give it a try and see for yourself.

ultrauber (author)2009-01-03

Good to know.

Orngrimm (author)2013-01-07

but 155dB and more is not only ear destroying but also quite power-consuming.
And such loud systems tend to be dangerous since if you forget the proper ear-protection if you start, you propably dont need to worry over ear-protection in the future ever again...

dippitydip (author)2011-12-10

600Hz, not 600kHz.

Josehf Murchison (author)2013-01-06

I have see this done a number of difrent ways in most cases it is not the sound but rather the air the sound is moving getting under the object and lifting it. I have seen a person use a speaker and a sheet of paper cut to look like butterflys levitate the butterflys.

xienwolf (author)2014-02-08

For those coming across this comment who don't know: Sound IS the air. Sound is compression waves, and compression waves mean squishing lots of the medium into a small space. So with a strong sound, you get highly compacted air, which means more dense air. And just as with water, anything less dense will float.

sansoy (author)2013-11-02

Here's great article/video on making one on the cheap!

guyfrom7up (author)2008-04-04

hmmm.... seems to me like there's a ton of variables that an ordinary person can't tackle, you need to know the mass of the object, and then carefull adjust the frequency and the distane in between the "speaker" and the "reflector."

NachoMahma (author)2008-04-04

. hmmmm I'm thinking that that the mechanical parts would be where any difficulties would lay. The oscillator(s) would be a pretty trivial item for an intermediate Electronic DIYer. Same with the power amp. The transducer should be an off-the-shelf item. Adjusting the distance should be trivial - a very-fine-thread, screwed pedestal shaft oughta work. From my POV, the concave (parabolic?) surfaces would be the hard part and they may be off-the-shelf items (tele/microscope lenses?).
. Not that it would be easy (out of my league), but I'd hate to discourage anyone from trying.
. Maybe I just don't understand what's going on. :)

killerjackalope (author)2013-01-07

The transducers in high power horns could handle it, cheap too, though they'd likely need a little cooling and might eventually die - since they're audible range designed...

Power amp might be more awkward, many will have filters built in, since ultrasonic frequencies can damage horns and more importantly having random spikes over 18Khz really hurts... I'm sure it can be done, though for this you could rig one using power transistors, it doesn't need to be a particularly awesome amp since it's generating a single frequency.

The parabola isn't much trouble - was reading up on this a while ago (since I have a bunch of equipment lying about anyway) it's basically a simple reflector for it, an easy shape to find...

If you want to experiment with frequencies and distances - get an old photo enlarger, perfect thing for raising and lowering vertically...

ultrauber (author)2008-04-04

whoa!

Spl1nt3rC3ll (author)2008-04-04

Goodhart (author)2008-04-04

he means it is complicated LOL

zerofootprint3 (author)2013-01-06

I would like to see an instructable on this, too. However, it is my understanding that the illustration is wrong. The reflected wave, on its way back down, creates a series of figure 8's. An hour glass shape, if you will. the levitation occurs where the sand would normally fall through in an hour glass. Hence, it creates a series of standing figure 8's.

Further, I do not believe you will hear anything, it is above the audible range.

Goodhart (author)2008-04-04

Some video concerning accoustics; hmmm

And some pics on how it is supposed to work:

Stonebear (author)2012-09-18

Stupid question but what would happen without the reflector?

Goodhart (author)2012-09-20

If the two sections between what is being levitated can not transmit the sound properly it''ll not be focused enough to do what it is supposed to do.

watson_loser (author)2010-01-06

i think there is impossible to do that way in home.. because you need extremely intense sound to produce the sound waves for acoustic levitation; usually this is over 150 decibels (is like standing near a jet-engine airplane as it takes off)... :D

lucas1123 (author)2009-01-02

you need at least over 155db at over 600khz this in its self is hard to achive