Overview

This project uses the idea of sustainability and the special properties of a material, ferrofluid, to create a sound visualization experience. The point is that there are many different types of energy around us, ready to be harnessed.

A lodestone is a piece of magnetic iron ore possessing polarity like a magnetic needle, and it was used for hundreds of years by sailors for navigation. The term "lode" comes from the Middle English and means "way".

The development of the project began with an instrument that Marc Buccheri demonstrated, which featured small magnets hitting chimes. When the chime box was turned over, the magnets would fall back, and the force of gravity on the magnets would again take hold. The gentle effect of the instrument was mesmerizing, and it was an elegantly simple use of a physical force. The cyclic nature of the process resonated with the idea of sustainability.

The initial thought was to make some instrument with falling, and then evaporating, water. However, it seemed more interesting to explore the properties of some less familiar substance. Ferrofluid, a fluid that contains iron in a substrate, was chosen: it was able to create beautiful, sculptural forms with only the force of a permanent magnet.

The initial experiments with pure ferrofluid did not yield sufficient visual results. Instead, the ferrofluid is constrained to a test tube, in which it is suspended in water. Electrical energy from a solar-powered battery pack is sent to a small audio amplifier. Ambient sounds are captured by a stereo microphone, amplified, and translated into movement of the ferrofluid by means of an electromagnetic coil. A lodestone is placed above the surface of the ferrofluid, so that it can interact with the ferrofluid's motion.

Experience

The look of the piece is reminiscent of a 19th-century scientist's cellar laboratory. It contains lab stands, wire, and the test tube, illuminated from the back by cold-cathode lighting. The lighting exaggerates the motion of the fluid, and since the lighting is cold cathode, it uses far less energy than a standard light bulb. The lodestone is suspended over the test tube.

A Tibetan singing bowl will be placed on a cushion in front of the apparatus. The user can hit the bowl with the puja, the wooden stick. The resonances from the bowl are picked up by the microphone and create spiky, regular, and animated sculptures. Ambient noise is also picked up by the microphone, but that noise moves the fluid in lumpy, irregular ways. The lodestone itself moves in concert with the ferrofluid (Newton's third law) and creates an interesting effect.

The Tibetan singing bowl was chosen because it had the greatest effect on the ferrofluid. It also uses the idea of hidden forces in its construction; mantras spoken during its making are purported to give it its resonance. It is also made from seven metals: gold, silver, mercury, copper, iron, tin, and lead--the stock-in-trade of an alchemist of yore.

A ferrofluid is a stable colloidal suspension of sub-domain magnetic particles in a liquid carrier. The particles are about 100 Angstroms in size, and are coated with a surfactant to keep the particles from clumping together (even when a magnetic field is applied). By volume, a ferrofluid is about 5% magnetic solids, 10% surfactant, and 85% carrier.

When no external magnetic field is present, the magnetic moments of the particles are random, and the fluid is not magnetic.

When an external magnetic field is applied, the magnetic moments of the particles orient themselves almost instantly to the magnetic field lines of the external source. When the magnetic field is removed, the particles go back to random alignment very quickly.

Ferrofluid is used in many industrial applications. Many kinds of loudspeakers are damped with ferrofluid. If you own a CD or DVD player, the laser head most likely has a drop of ferrofluid in there to damp it. It's used in sensors and switches, and for testing magnetic audio, video and data media (floppy discs, etc.) Some new bridges in windy or earthquake-prone zones use a thicker version of ferrofluid to damp movement. When the wind starts the bridge swaying, large magnets in the structure come closer to each other, and since ferrofluid gets thicker (more dense) in a magnetic field, it stops the bridge motion.

A ferrofluid will always tend to move to the region of highest flux. This can create some very interesting patterns when magnets of different shapes are used.

Energy Usage

The major use of power in this project is the power amplifier. The voltage at which the battery ran was measured 12.62 V with no load. Regarding the amperage, the rated overall consumption when using a stereo microphone was as follows:

- idle state: 1.143 A (at the maximum volume of the amplifier)
- with mic input: 2.4 - 3.3 A

Therefore, the rated power consumption of the current installation is:

- idle: 14.42 W
- with mic input: 30.39 - 41.65 W

We also measured the amperage drawn for the cathode tubes:

- two units of a two-cathode tube: 500 mA * 2 = 1 A
- two units with a 10K resistor: 250 mA * 2 = 500 mA

Even in the latter case, we didn't recognize a significant drop in  luminosity, so using a resistor will be a good plan for decreasing the amperage  for the cathode unit(s), which we estimate:

- 6.31 W (one cathode unit)
- 9.47 W (one cathode unit with a 10K resistor)

The amplifier we chose runs on 12V DC power, so it may operate off the un-inverted output of the solar battery pack.