Introduction: Acoustic Tractor Beam

Picture of Acoustic Tractor Beam

Tractor Beams are mysterious waves that can attract particles towards the source. Here, we will show you how to build an Acoustic Tractor Beam with components that can be bought directly on the Internet for less than 75$.

With this Instructable you will be able to get in your hands a device that it was only seen on SciFi movies such as Star Wars or Star Trek.

If you want more scientific background on Acoustic Tractor Beams, you can check our Open Access research papers:

Do not forget to watch the attached video in this Instructables.

If you want to build other devices coming directly from the research lab keep in touch:

Twitter: @AsierMarzo

Step 1: Gather the Parts and Tools

Picture of Gather the Parts and Tools

We present a list of the necessary components. I have tried to place links for different countries. However, the same parts can be found all around the world, some useful websites are

The circuit is not complicated. Basically, an Arduino will generate 4 half-square signals at 5Vpp 40kHz with different phases. These signals get amplified to 25Vpp by the Motor Driver and fed into the transducers. A button pad can be used to change the phases so that the particle moves up and down. A battery (7.3V) powers the Arduino and the logic part of the Motor Driver. A DC-DC Converter steps-up the 7.3V to 25V for the Motor Driver.


  • 30x 16mm 40kHz Transducers The MSO-A1640H10T are the best but minimum order is 500, they are good so perhaps you can save them for future ultrasonic projects. Alternatively, others 16mm 40kHz transducers will serve (emitters and receivers are pretty much the same) for instance the MCUSD16P40B12RO.

Necessary Tools:

  • 3D printer -> you can use an online service
  • Soldering Iron, Tin and Flux.

  • Drill

  • Hot-glue gun

  • Multimeter

  • Cable Peeler

  • Screwdriver and Pliers.

  • Oscilloscope with two probes (Optional) -> you can get one for less than 50£

Step 2: 3D Print the Bowl

Picture of 3D Print the Bowl

The transducers will be mounted in this bowl. This shape allows to naturally focus the beam.

We used an Ultimaker Extended 2+ with a 0.4mm nozzle and the Normal settings. No support, only brim. It does not need to have a perfect finish so any regular printer should work.

You can also use the case created by DanielN253, it is available in Thingiverse

Step 3: Solder Arduino Headers (upwards If Possible)

Picture of Solder Arduino Headers (upwards If Possible)

Step 4: Program Arduino

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Upload the attached program in the Arduino Nano. If you are using a cheap Nano (totally recommendable) you will need to install new drivers, there are usually links in the webpage where you bought it.

Step 5: Charge the Battery

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This way when you finish the project it will be at full charge.

Step 6: Cut the Handler

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300x45x15mm rectangular piece of wood.

Step 7: Redrill the Bowl

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Sometimes the holes are not perfect and are a little bit clogged, re-drill them if it were necessary.

Step 8: Attach the Bowl to the Handler

Picture of Attach the Bowl to the Handler

Drill an initial hole in the handler, attach the central screw and then you will be able to drill the two holes at the sides.

Deattach the bowl, it is more comfortable to attach and test all the components without the bowl. At the end of the Instructables we will reattach it.

Step 9: Screw the DCConverter and the Driver

Picture of Screw the DCConverter and the Driver

Close the the drilled holes for the bowl we will place the DC-DC converter at one side and the Driver at the other. Put them and mark with a pen to drill later. Then pass a screw and a nut through the holes of the devices for being able to attach them properly to the wood.

It is very important to leave the OUT side of the Converter closer to the bowl.

Remove the indicated jumper of the Driver and keep it for later.

Step 10: Stick the Arduino

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With Velcro tape, double sided tape or just hotglue stick the Arduino below the Driver with the USB port pointing to the right.

Put the jumper between the D10 and D11 pins.

Step 11: Drill Through Holes

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Drill two through holes above the Driver.

Drill tree through holes below the Arduino.

We will pass wires through these holes.

Step 12: Solder Wires to the Power Switch

Picture of Solder Wires to the Power Switch

The central pins provides the current to the circuit, the right pins go to the DC barrel and the left ones to the battery connector pins.

Try to use red wires for (+) and black for ground (-) to keep things ordered. Pay attention to where the + and - of the DC barrel go and solder it appropriately.

For the battery connector pins we can use pin headers and a tiny piece of strip-board. Be sure that the wires are not touching each other (use a multimeter), and even put hotglue between them to make them safer.

The power switch provides current to the circuit either from a DC barrel or from the battery.

We can use any DC adaptor between 9V and 12V that can provide at least 2A if you do not want to use a battery.

Step 13: Stick the Battery

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With double-sided or Velcro tape. Do not use hot-glue since it could damage the battery. Put it in the same orientation as the image.

Step 14: Connect the DCConverter With the Driver

Picture of Connect the DCConverter With the Driver

These wires will pass the step-up voltage (25V usually) from the DCConverter to the Driver.

Step 15: Glue the Power Switch

Picture of Glue the Power Switch

Step 16: Connect Logic Supply

Picture of Connect Logic Supply

We will provide 7.4V to the DCConverter IN.

First connect the black ground wire (-) from the central pins of the Switch into the DCConverter IN(-). In the same hole connect the ground for the Arduino.

Then, connect the red (+) wire from the central pin of Switch into the DCConverter IN(+). In the same hole put the VIn of the Arduino, and the logic supply for the converter (pins from where we removed the jumper, very important to connect it into the highlighted pin).

Tining the tips of the wires will facilitate putting several wires in the same hole.

It is also possible to get voltage for the Arduino from the DCConverter. Instead of connecting Converter.IN(+) to Arduino.VIn, we can use DCConverter(5V) to Arduino(V5).

If it is too difficult to put various wires into the sockets of the DCConverter, you can also solder to the pads that are at its sides.

Step 17: Connect Signal Wires

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These four wires will transfer the signals from the Arduino into the Driver.

Connect Arduino.(A0,A1,A2,A3) to Driver.(IN1,IN2,IN3,IN4).

Step 18: Button Pad

Picture of Button Pad

The button pad is optional, but if you make one you will be able to levitate the particles up and down.

The idea is to have three button pads that when pressed they make contact with ground (the buttons are active low).

Get ground from the Arduino to the common terminal of the buttons. Then, connect each of the buttons to D2(up), D3(down) and D4 (reset position).

Step 19: Set the Voltage to 10V

Picture of Set the Voltage to 10V

First Connect the battery (be sure to use the right polarity).

Switch on the device.

Rotate the potentiometer counterclockwise until you see 10V in the display.

In the final device we will use 25V but it is safer for the test equipment to work at 10V. If you use X10 probes then it is alright to use 25V throughout the process.

Step 20: Test the Signals

Picture of Test the Signals

This step is optional but it is about time to check that everything is working fine.

Get two probes and connect the grounds to a ground of the circuit, temporarily using the button pad ground is one of the easiest options. Remember to put it back when finished.

Before the driver the signals should be 5Vpp and after the driver 10Vpp.

Signals from the same side are in phase while signals from opposite sides should be out of phase.

Step 21: Mark Polarity (Recommended Method)

Picture of Mark Polarity (Recommended Method)

The easiest way to mark the polarity is to use the Arduino itself. This method does not require an oscilloscope or to poke the transducers inside.

Install the code from this section into the Arduino. Connect one wire to A0 and another wire to GND. While the Arduino is connected to the PC, run the Serial Plotter (Tools->Serial Plotter) and be sure that the speed is set to 115200. When a transducer is connected between A0 and GND the signal will do one of the following things:

  • Signal goes down or remains at 0. Then, mark the leg connected to GND.

  • Signal goes up or remains at 1023. Then, Mark the leg connected to A0.

  • It is important to not touch the transducers leg or the wires while doing that or the values will reset.

If it is still not possible to detect the polarity, poke the inside of the transducer with a thin wire and check if the spike goes up or down (like in the obsolete method). Spike up -> mark A0 leg, spike down -> mark GND.

Step 22: Mark Transducers (Obsolete Method)

Picture of Mark Transducers (Obsolete Method)

This method for marking transducers is much easier than the previous one.

Just connect one probe to the transducer.

With a metal wire poke gently and repeatedly the inside of the transducer. Check the signal in the scope, if the first spike goes up, mark the ground leg. If the spike goes down, mark the other leg.

Step 23: Mark the Transducers (Obsolete Method)

Picture of Mark the Transducers (Obsolete Method)

The transducers have polarity and they need to be marked. Do not trust manufacturer marks since they can be wrong.

This method is the one contained in the video, but we have an alternative one that is much easier one in the next step.

First take ground and voltage from any of the Driver outputs. Connect them to a transducer and also connect one probe to the same transducer. This probe will capture the emitted signal.

Take another probe and connect it to the transducer that needs to be marked, this will be the received signal.

Put the transducers face to face and check the signals in the scope.

If the signals are in phase, mark the leg connected to ground. If they are out of phase, mark the other leg.

Mark all the transducers.

Step 24: Mount the Transducers

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Put the transducers in the sockets with the marked legs pointing upwards (towards the top).

You do not need to populate the bottom row.

Step 25: Wire the Transducers (hard Method)

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We need to wire the transducers to deliver power into them.

Measure the needed length for the wire and give three extra hands for connecting it later.

With the cable peeler, partially peel at the correct distance, later these exposed parts will be twisted around the transducers legs.

Once that you have made the cuts with the peeler, redistribute the plastic to keep a uniform length of cooper exposed. Twist the cooper wires to make them more solid. Twist the exposed parts around the transducers legs, apply flux and solder.

Follow the pattern presented in the images. That is, all the grounds are connected together. The red wires of the same half go towards the same side.

Pay attention to the numbers, these numbers correspond to the driver numbers.

Step 26: Wire the Transducers (Simple Method)

Picture of Wire the Transducers (Simple Method)

It is the similar to the other method but using exposed wire.

Step 27: Test the Transducers

Picture of Test the Transducers

This step is optional but it is convenient to check that all the transducers are connected correctly.

Connect the ground from the bowl into the driver ground (there will be another wire there).

Connect the 4 red wires from the bowl into the outputs of the Driver, respect the numbering.

Connect two extra marked transducers to the scope probes. Be sure to connect the ground into the marked leg (or at least connect the two transducers in the same way). With these transducers we can check the emitted signal of other transducers.

Transducers from the same half of the bowl should emit in phase. Transducers from opposite halves emit out of phase.

Transducers with the wrong polarity should be desoldered, rotated and resoldered.

Step 28: Set Voltage to 25v

Be sure to set the DC-DC converter to 25V using its potentiometer.

Step 29: Attach the Bowl

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Now that all the components are in place, it is time to reattach the bowl into the handler.

Step 30: Connect the Wires

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Connect the ground from the bowl into the driver ground (there is already another wire there).

Step 31: Switch on and Levitate

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Switch on the device, you should be able to feel a little bit the sound, or hear it if you point it into a big chunk of expanded polystyrene or foam.

Using an acoustically transparent sheet or tweezers you can place particles in the centre of the bowl (above 1.8cm approx) and they will be levitated.

Push the buttons to move the particle up or down.

Depending on the size of the particle and how close it is to the bowl, you will be able to levitate it laterally or upside down. It is also possible to levitate particles that are resting on a surface.

Step 32: Building Other Sonic Devices (Optional)

We have presented how to build the most efficient device but there are others that require even less electronics although they are not as efficient in terms of levitation power to watts.

For the following devices you will need smaller transducers, wires and connectors, as well as a different version for the Arduino (that generates always a 40kHZ signal).

Step 33: Coils Device (Optional)

Picture of Coils Device (Optional)

Print the attached STL file. The transducers are fit in the bottom holes and they are all driven with the same signal.

Step 34: Tubes Devices

Picture of Tubes Devices

Print the attached STL file. The transducers are fit in the bottom holes and they are all driven with the same signal.

Step 35: Miscellaneous Files

Raw design files (Inventor)


DanielN253 made it! (author)2018-01-08

Thanks Asier Marzo for a great project! Here I made an enclosure for the Acoustic Tractor Beam which is open for download at Thingiverse, see link:

Asier Marzo (author)DanielN2532018-01-08

That is amazing man. would you mind if I put in the main text? of course crediting you.

DanielN253 (author)Asier Marzo2018-01-08

Please do! I'll make sure to add in more details about the components I used in the build.

Dangerously Explosive (author)2018-01-08

Dang. This thing is awesome.

Now, if you used larger transducers and/or increased the input power, could you extend the range (for smaller objects) or increase the strength for handling larger particles (short range)? Levitating an object from across the room and pulling it to oneself is the goal I have in mind.

I was also wondering, if you had a bunch of servos or stepper motors, could you change the angles of the transducers in sync and have it still work (again to increase range)?

Lastly, have you considered adding a small laser diode to the center of the bowl, pointing straight out, so that you know what the tractor beam is aiming at?

glad that you like it.

- More power could be used for heavier objects. For larger objects you need lower frequency. In this instructables we make a levitator that can levitate liquids and plastics:

- I think that levitating an object across the room would be great but sounds attenuates very quickly. Some things that we are testing are surface waves (the object is resting on a surface), electrostatic and magnetic forces.

- In all the designs I try to keep the price as low as possible but the laser is quite a cool idea.


hodgepodgerama (author)2018-01-03

Another question... Technically, the small transducers are generating a sound pulse, but the actual "tractor" is caused by the moving air created by the sound, correct? I have seen acoustic devices that simply use a single speaker in a parabolic enclosure with holes carefully drilled into it to create small air jets, much like your 3-d printed reflector. The air then pulses through the small holes in a jet like fashion, probably producing a very similar air-movement, holding a foam ball in a similar way. The difference, I think is that your device uses much higher wavelengths and therefore keeps the held items very still. But the overall effect is the same. Does this make sense, or am I missing some concept that applies here?

Thanks again for sharing your awesome project!

I'm not sure, but I think this one has more to do with the nodes and anti-nodes generated by the sound waves than with air movement. The bowl simply focuses the nodes/antinodes on a particular point in space, creating a pocket where a particle can be held at rest. The reason ultrasound is used is because it is at a high enough frequency to allow fine tuning and manipulation of this point in space, with little detrimental effects to the human ear, as well as having a more precise range with less input power. I do not believe the air has much to do with it, other than being the medium though which the waves travel. With air jets, the particle cannot be held upside down without having a jet source underneath it, which defeats the point of the tractor beam, whereas the ultrasonic nodes/anti-nodes allow the emitter to be in any position and still hold the particle in place.

Asier Marzo (author)2018-01-02

No worries man, this was the first one. The new ones all have narration.

danbrown655 (author)Asier Marzo2018-01-03

Actually, I don't know what's up with DaDawei and his lack of good music with a beat, but I like it. What is the name of the song and the group?


Asier Marzo (author)danbrown6552018-01-03


DIY-Guy (author)2018-01-03

This is beautifully documented.
I subscribed to the YouTube channel right away!
I'll be doing a "follow" here as well.

Asier Marzo (author)DIY-Guy2018-01-03

Thx man, I will try to keep improving and posting some of our research projects. Next one is a directional speaker.

hodgepodgerama (author)2018-01-03

This is a ridiculously cool project and I love doing this type of thing, but I am afraid it will end up on my "finish eventually" shelf along with the 2 or 3 other projects that are there now. The optional tabletop "tube devices" repulsor beam device actually looks like a more practical thing that you could set on your desk. I'll put this on my wish list.

I'm curious. What kind of sound is generated by the device?

Glad that you like it. Here we use ultrasound (40kHz) it is different from air jets since they compress and expand the air, there is no medium flow or movement. You can levitate things through fabric and also upside down. Check for liquids levitation.

YaënD (author)2018-01-03


BillE61 (author)2018-01-02

Wow neat! This looks familiar to me. The Manhattan Project (1986) lol

RumpelS (author)2018-01-02

You should link the video directly here which demonstrates your beam in action! I read your entire article without understandiung what it is talking about!

상우지 (author)2017-11-29

It is great stuff I ever met in Bristol University's project. I like it.

I think it has great feature for many applications. but there will be needed work together for its testing and development for commercial development. I asier also working for Birstol Univerisity or Ultrahaptics..

SidewinderPathfinder (author)2017-11-25

How do you set up the Oscilloscope to test the transducers? I am trying the obsolete method because I could not get the adruino method to work. I am trying the 'poking' method with one transducer hooked up to my oscilloscope, I just do not know what settings it should be set to to get the graphs that are shown in the instructions.

Thank you,


Spikes will be around +-500mV and the sampling rate is slow enough so that you see the sampling scan advancing on the scope. It is more clear in the video. Best, Asier.

JuanV161 (author)2017-11-20

Hi !

I want to know if you calculated the force exerted by the acoustic pressure field on the ball?

or if you have some paper wich could help me, I'm working on this project and i have to get so much information as possible.


Asier Marzo (author)JuanV1612017-11-21

Sure, soon I will put an instructables and video but for the moment this paper could be useful it has a link to the github code, and the videos are in

farhaneden (author)2017-11-20

hello asier, why must we put the jumper between the D10 and D11 pins.?

Asier Marzo (author)farhaneden2017-11-20

It is to synchronise each period. The external timer outputs 40kHz at D10 and we use D11 to control the main loop. more info in

Hitchhiker_42 (author)2017-10-13

ive constructed this to the best of my ability but it's still not functioning properly

Could you describe the problem? All the lights are on? transducers marked correctly? how many volts are you putting in the DCDC converter? Best.

i've narrowed it down to one problem, one side it stronger then the other. however I do not know exactly why but a possible reason is that one side is getting half a volt more then the other, could that be why it isn't working?

Half a volt is not very significant. Perhaps the driver is broken?

the driver appears the function just fine, i've rewired the sound bowl with all new parts and it is still not functioning, it can push the polystyrene beads but it will not pick them up.

At the end of the video it is shown how to place the particles in the levitator.

jmyers03 made it! (author)2017-10-30

Hello Asier,

We are currently trying to model the force field from the Gork'ov Potential, and we are unfortunately getting highly unstable system results. However, our experimental prototype does not have such instability problems.

We are using three rows of transducers in a close-packed configuration in a top and bottom spherical bowl configuration. When using the complex exponential pressure field, then doing the Gork'ov Potential, we get pressure field nodes that are not stable under lateral movement.

To clarify what we believe the math represents, refer to SI AM4 from your TinyLev publication. Using the pressure field equation at the top of the document, summing the contributions for each emitter, and taking the absolute value, we attain a pressure field that is very similar as the one that you display in your publication. Further, we believe that we have this part write. However, using the equation for the Gork'ov potential and taking the negative gradient of it, we attain divergent force vectors as displayed in the image attached. We are wondering if you had ever had this problem. We are levitating small, roughly spherical pieces of paper, which have taken to have equivalent properties to wood (cp and rowp).

Please comment if you have had similar problems in any way. We are using MATLAB's gradient function for px, py, pz and F=-Del(U).


Camilo04 (author)2017-10-29

Hello Asier,

We are currently on a budget and we do not have an oscilloscope. I was wondering if there was a different way to test he transducers?

Asier Marzo (author)Camilo042017-10-30

I was testing right now if it is possible to do it with the same ArduinoNano. I will report ASAP.

_electronicguy (author)2017-10-20

Hi Asier, first off thanks for sharing this wonderful project. I saw this video ,It is definitely great job!

1) I am keen to build the Ultra tongs from the following video:

Is there a way you can share arduino code or does the code with TinyLev hold for this? I assume i will need 16mm transducer.

2) I read through the research paper linked (great paper by the way, i could easily grasp the principles at work here ) so here is levitation it due to two waves out of phase moving opposite direction producing standing wave or the central transducer is out of phase with the ones around it?

3) Would i still need 2 outputs of driver or is just one output connected to opposite terminals of transducer at centre?

Thank you


Glad that you like it.

Building UltraTongs should be easy and cheap. You need 2x7 10mm diameter transducer for each.

I would recommend the driver board from the Instructables "Acoustic Levitator" it is simple and uses push-pull (double the voltage on the transducers) otherwise you can just use the tractor beam circuit with 24V on the DC converter.

Using the Acoustic tractor beam driver. Connect one channel (OUT1 for instance) to the positive legs and GROUND to the negative legs of the transducers of the 6 outer transdsucers, The inner transducer should be connected with reverse polarity (GND to the possitive and OUT1 to the negative). You can use different OUTs for each 7-transducer array to balance the load.

Using the Acoustic Levitator driver, connect OUT1 to the positive legs and OUT2 to the negative legs (please reverse the polarity of the central transducer). If you use OUT1&OUT2 for the bottom array and OUT3&OUT4 for the top array, you will be able to move particles up and down.


RocketPenguin made it! (author)2017-10-12

Worked with half as many transducers as needed, albeit not as well as it would have with all of them (The Chinaman I purchased them from couldn't count, and so I only got half my order.) I plan on making the full levitator sometime soon...

jennywang5640 (author)2017-10-09

In this link,can purchase 100PCS MSO-P1640H12T directly.

ain reduan (author)2017-10-09

hello asier. im doing this project as my final year project but i changed some of it which i didnt used button to levitate the bead. im having a problem with the coding right now. do u know the new coding that i should used? if u didnt mind, can u help me?

thank you for the concern.

Asier Marzo (author)ain reduan2017-10-09

Hi Ain,
You can use the code provided in the instructables. What short of modification you would like to make to it?


CKapahi (author)2017-09-18

Hi, I was curious how the up and down buttons controlled the focal point of the speakers. I tried to read the Arduino code, but it still wasn't clear to me whether the focal point was being altered by changing the frequency the speakers were driven at, or changing the phases of the speakers somehow. Thanks for making all this so easily available by the way!

Asier Marzo (author)CKapahi2017-09-19

Hi, glad that you like it.
to move the focal point we change the phases. Each period is divided into 24 steps of 0s and 1s by shifting the patterns we change the phase:
000000000000111111111111 -> phase 0
000000111111111111000000 -> phase pi/2

the phases are precalculated for the different points and hardcoded in the code (that is why there are a lot of hex constants).

jcwildfire (author)2017-08-11

Hello, thank you very much for the how to on this. I am apart of a school project that is building the pinch set up. However, we are having trouble with transducers. We cannot hear them making any sound to speak of, and the voltage out of the driver is .1V. The Arduino is responding to all commands that we give it, and the dc-dc is working well with its outputs. We have tested the transducers to properly mark positive and negative legs. have you experienced an issue like this?

Asier Marzo (author)jcwildfire2017-08-13

Could you post some pictures of the driver?
Are all the red lights from the Arduino, DCConverter and Driver on?

jcwildfire (author)Asier Marzo2017-09-08

Thank you very much for your response. We managed to get it working temporarily (fantastically I might add), however, when we tried to drop the voltage to see how that would alter the acoustic trap, the unit stopped working. We tried for awhile to get it back. Do you have any suggestions?

The original problem was the Lan Driver was bad.

Asier Marzo (author)jcwildfire2017-09-09

How low the voltage went? the ideal value would be 20V int the DCDC converter. It will not be able to produce less than the input voltage.

Do you have a scope to test if the Arduino is generating the signal and if the driver is amplifiying it?

jcwildfire (author)Asier Marzo2017-09-10

Yes we have a scope. We will test that these components this coming week. The voltage was down around 23 V and .22 A when working, the issue we had arises at around 16 V.

The nano is getting warm now with a voltage of less than 10 V. I think i may need new components.

Asier Marzo (author)jcwildfire2017-09-11

With the scope you should be able to check if the Arduino is generating logic signals and if the Driver is amplifiying them. I recommend running the device at 20V (no more than 25V) I think it should consume more amps at that voltage.

jcwildfire (author)Asier Marzo2017-09-08


jcwildfire (author)2017-09-08

Thank you very much for your response. We managed to get it working (fantastically I might add), however, when we tried to lower the voltage to see how that changed the acoustic trap, the unit stopped working above the given voltage. Do you have any suggestions?

The original problem was that the Lan Driver wasnt working properly, and we had a different set of transducers that could not provide the proper frequency.

Hello Asier,

Thank you for sharing the instructions of this device. I'm actually trying to go a step further with the acoustic levitation by making a device with four phased array able to manipulate objects with ultrasounds. And while I was searching documentation, I found your device called Levipath. And by reading it's PDF, I wanted to ask you how you are able to change the phase of the signal of the speakers. So can you explain that to me or at best share the computer code of Levipath.

Best regards

About This Instructable




Bio: Build your own cutting-edge devices coming directly from the research lab. Ultrasonics, electromagnetism and more. Researcher at Bristol University interested in Ultrasound and in general ... More »
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