Levitating Speaker Plays Back Eerie Recordings

Levitating Speaker

Let’s face it, levitating anything is pretty fascinating — especially when you think there should be wires. This project puts a new spin on magnetic levitation by using a PID controller to levitate a speaker while it plays music!

It uses the standard levitation setup — an electromagnet, a permanent magnet, and a hall effect sensor. A microcontroller implements the PID system, varying the current supplied to the electromagnet to keep the speaker floating at just the right height. Music is wirelessly transmitted to the speaker via Bluetooth, but unfortunately the speaker’s power is not. It features a small lithium ion battery which has a run-time of around 5 hours before it has to be recharged manually.

As you’ll notice in the following video, having a floating speaker has a pretty interesting effect — especially when it starts spinning.

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The Old Ping-Pong Ball Levitation Trick

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[Jacob] has put a slightly new twist on the levitating ball trick with his ping-pong ball levitation machine. We’ve all seen magnetic levitation systems before. Here on Hackaday, [Caleb] built a Portal gun which levitated a Companion Cube. Rather than go the magnetic route, [Jacob] levitated a ping-pong ball on a cushion of air.

Now, it would be possible to cheat here, anyone who’s seen a demonstration of Bernoulli’s principle knows that the ball will remain stable in a stream of air. [Jacob] proves that his system is actually working by levitating ping-pong balls with different weights.

A Parallax Ping style ultrasonic sensor measures the distance between the top of the rig and the levitating ball. If the ball gets above a set distance, [Jacob's] chipKit based processor throttles down his fans. If the ball gets too low, the fans are throttled up. A software based Proportional Integral Derivative (PID) loop keeps the system under control. A graph of the ball distance vs fan speed is displayed on an Android tablet connected to the controller via USB.

When [Jacob] switches a heavy ball for a light one, the lighter ball is pushed beyond the pre-programmed height. The controller responds by reducing the fan speed and the ball falls back. Who said you can’t do anything good with a box of corn dogs?

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3D Acoustic Manipulation: Seemingly-Unreal Levitation Using Soundwaves

floating

Wow. [Yoichi Ochiai], [Takayuki Hoshi] and [Jun Rekimoto] are researchers from the University of Tokyo and the Nagoya Institute of Technology, and they have just learned how to airbend.

Using a series of standing ultrasound waves, it is possible to suspend small particles at the sound pressure nodes. The acoustic axis of the ultrasound beam is parallel to gravity, which also allows the objects to be manipulated along the fixed axis by varying the phase or frequencies of the sound. By adding a second ultrasound beam perpendicular to the first it is possible to localize the pressure node, or focal point, and levitate small objects around a 2D plane.

In their demonstrations they float foam particles, a resistor, an LED, they show off the waves using a piece of dry ice, and even manage to float a small screw.

Sound like crazy talk? Just watch the video.

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Acoustic levitation of water droplets

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These water droplets are not falling; they’re actually stuck in place. What we’re seeing is the effects of an acoustic levitator. The device was initially developed by NASA to simulate microgravity. Now it’s being used by the pharmaceutical industry do develop better drugs.

The two parts of the apparatus seen in the image above are both speakers. They put out a sound at about 22 kHz, which is beyond the human range of hearing. When precisely aligned they interfere with each other and create a standing wave. The droplets are trapped in the nodes of that wave.

So are these guys just playing around with the fancy lab equipment? Nope. The levitation is being used to evaporate water from a drug without the substance touching the sides of a container. This prevents the formation of crystals in the solution. But we like it for the novelty and would love to see someone put one of these together in their home workshop.

Don’t miss the mystical demo in the clip after the break.

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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.

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Frustrating fun with magnetic levitation

[Andrey Mikhalchuk] built his own magnetic levitation device and you can too… if you have the patience. He’s not using electromagnets, like the Arduino levitator or the floating globe. Instead, a pair of ceramic ring magnets and a few hours are all it takes.

The base of his device is a couple of very large ring magnets that would most often be used in speakers. It’s hard to see them in the image above because there’s an inverted plastic container obscuring them. A second (or third depending on how you’re counting) ring magnet is selected because it is smaller than the circular void in the magnetic base. It’s impossible to simply balance the magnet in the air, but spinning it is a different story. By creating a perfectly balance magnetic top, then spinning it inside the magnetic field of the base, you can leave it floating in mid-air.

Check out the video after the break. It’s a neat effect, but you really do have to have a perfect setup for it to work. [Andrey] mentions that it takes a couple of hours to fine-tune. And if the ambient conditions change slightly, it throws the whole thing off.

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Arduino levitation

Here’s the proof that Arduino is a tool for serious prototyping and not just a toy. [Norbert Požár] built a magnetic levitation device that combines an Arduino with an electromagnetic driver circuit and a magnetic field sensing circuit. Unlike other other levitation setups that use optical sensing, this implementation uses a hall effect sensor on the electromagnet to maintain the distance between it, and the permanent magnet it is holding in midair. Check out the embedded video after the break and browse through the overview page so see how pleasing it is to do away with a frame around the floating object. This makes us wonder if it could be inverted in a way similar to that magnetic scale.

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