L Levitating LED Light

Proposal
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L3
Levitating LED Light
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ECE 4007 Senior Design Project
Section L03-04, Team L3
Inga Shvartsman
Shruti Batra
Chris Melton
Andy Givens
Harold Kimball
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Submitted
September 22nd, 2010
Table of Contents
Executive Summary ......................................................................................................... iii
1. Introduction ............................................................................................................1
1.1 Objective ..........................................................................................................1
1.2 Motivation ........................................................................................................2
1.3 Background ......................................................................................................2
2. Project Description and Goals ..............................................................................4
3. Technical Specification ..........................................................................................4
3.1 Levitation .........................................................................................................4
3.2 Wireless Induction and Audio Oscillation .......................................................8
4. Design Approach and Details ................................................................................8
4.1 Design Approach .............................................................................................8
4.2 Codes and Standards .....................................................................................12
4.3 Constraints, Alternatives, and Tradeoffs .......................................................12
5. Schedule, Tasks, and Milestones.........................................................................12
6. Project Demonstration.........................................................................................13
7. Marketing and Cost Analysis..............................................................................14
7.1 Marketing Analysis ........................................................................................14
7.2 Cost Analysis..................................................................................................15
8. Summary ...............................................................................................................16
9. References .............................................................................................................17
Appendix A .......................................................................................................................18
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Executive Summary
The Levitating LED Light is a lit orb that levitates in air and allows its users to wirelessly
illuminate their households, offices, classrooms, restaurants, bars etc. This product also has the
ability to bounce up and down to the beat of music, which makes it a particularly interesting
device for the night club industry as a lit orb floating in the air and moving up and down to the
music, it has great potential to attract people to a club. Its function is based on the principles of
electromagnetic induction wherein a plastic ball with a rare earth ( Neodymium) magnet inside
its “North Pole” will be suspended in a magnetic field using a magnetic coil above the ball
controlled by a current regulating feedback loop using hall effect sensors. Attached to the ball
will be LED lights powered by a second coil above the orb feeding a time varying flux to a
“receiving” coil inside the floating orb. The current will be rectified and used to power the LEDs.
The larger device envisioned of which this product is a subsystem can manually be adjusted to
hover at a desired height and at the user specified amount of luminous intensity.
L3 is priced at $93 but essentially replaces the household bulb with a new light source
that can wirelessly be placed anywhere in the house and turned on and off at the users will. The
fact that it responds to the base of music, makes it a multipurpose light bulb that apart from being
a crucial household application also demonstrates the technological advancement in the field of
electromagnetics. L3 will primarily be marketed to night clubs and bars as they belong to an
industry where attracting large numbers of people is crucial to the clubs profits.
L3 competes with products in the market that allow a user to levitate basic objects such as
a globe or a light frame, but these products don’t have the ability to illuminate their surroundings
or to bounce to music. The Galileo Gravitator Lamp and Crealevs edition of magnetically
levitating devices are examples of products that could potentially compete with L3.
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1. Introduction
Project engineers will design and prototype a light bulb that levitates in air and has the
ability to bounce up and down to the beat of music to achieve wireless control of the amount of
light shining in a room.
1.1 Objective
The L 3 (Levitating LED Light) is a glowing orb that levitates in air under the influence
of electromagnetic radiation. The L3 essentially consists of a plastic ball that has LED lights
attached to it and these lights instantaneously turn on when the ball is placed in the
electromagnetic field. This ball has the ability to float 2-6 inches below a control box, which may
be placed in or attached to the ceiling. L3 also has the ability to bounce up and down to the beat
of music because it is placed in a magnetic field that is constantly changing with time.
The L3 is priced at $93 and will primarily be sold to proprietors of night clubs and bars in
large quantities. The vision was to enter a night club with a hundred L3’s placed across the
ceiling of the club, bouncing up and down to the beats of trance music, and attracting everyone
who passes by. A similar device, the Galileo Gravitator Lamp, consists of a levitating globe used
to accessorize households and to visually demonstrate the basic concepts of magnetism to middle
school students. Although the Galileo Gravitator Lamp priced at $81.99, is $11.01 less than L3, it
does not offer the additional features that L3 does; alternatives to the Levitating LED Light do
not have the ability to light up in a magnetic field, nor can it bounce up and down to the base of
music.
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1.2 Motivation
L3 will cost $93, versus the Gravitator Lamp at $81.99, though we wish to improve on
this design by creating a greater luminosity, levitation distance, and the additional application of
vertical movement to music as well as extensive safety measures. The above mentioned technical
features are mentioned in detail with their respective mathematical values in the technical
specifications section. The L3 will meet all building codes and necessary requirements for safe
installation in the service and hospitality industries. A “fail safe” will be included in the event of
a power loss, the magnetic pull of the Neodymium magnet will take over and pull the entire
floating orb towards the control box instead of dropping it on patrons below.
The reason to do this project was to perform a task as trivial as the lighting of a bulb in a
way that allows wireless control of the amount of light shining and the height at which the orb is
levitating. In the process of wirelessly lighting up a club/household, we also wanted to
simultaneously demonstrate progress in the field of electromagnetics. The L3 will have a higher
MSRP than its competitors because it should meet all building codes [1] and necessary
requirements for the safe installation in the service and hospitality industry. The hypothetical
situation described above perfectly fits the night club atmosphere and this essentially summarizes
our motivation for this project.
1.3 Background
The levitating orb consists of magnets with coils wound around them which are further
connected to an LED + capacitor circuit in parallel configuration. The orb that we create can
suspend up to 3lbs. of circuit components at a distance of 2 inches above ground. A similar
device, showcased on Gizmodo has the ability to light up an entire room with high luminous
intensity, a portable control module, and consists of a rare earth magnet that achieves a higher
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value of magnetic field than the Neodymium magnet used by L3 . Object can levitate by
inserting the rare earth magnet inside it, fastening the controller above the desired suspension
location, then placing the object in the magnetic field. Figure 1 demonstrates the layout and
components of this system. Before discontinuing production in 1995, the Crealev limited edition
Maglev structure sold for $90,000 [2]. Another company, Blueberry Technology [1], currently
offers a line of levitation devices for retail and hospitality industries to display items in storefronts, lobbies, etc. These products are magnetically suspended on top of a fixture and sense the
magnetic field from below. This type of levitation is costly and less stable than levitation from
above. The Crealev floating lamp demonstrates the concept of magnetic levitation by making the
lamp shade hover over the fixture [2]. On the basis of the above analysis, it can be concluded that
although there are products in the market that magnetically levitate objects in air, those objects
cannot light up instantaneously or bounce up and down to music beats and still sell at $93.
Figure 1. iPod connects to the control box which regulates the illumination
of the LEDs as well as the vertical bouncing of the orb to the music.
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2. Project Description and Goals
The goal of the L3 project is to provide an entertaining and intellectually stimulating way
to illuminate a small, desk-sized area. The L3 will magnetically levitate and wirelessly transfer
power to a LED fixture. The L3 will also have the option to connect an audio signal to the device
which in turn will cause the levitating LED fixture to move up and down with the base from the
audio signal. The L3 will have the following properties:
•
Magnetic levitation of LED fixture
•
Wirelessly transfer power to LED fixture for illumination
•
Move up and down to the base from an audio signal
•
Plug directly into 120 VAC electrical outlet for power
•
Lightweight, durable PVC frame
The target user for the L3 is anyone who currently uses small lighting fixtures in their
home or office. Also, the musical feature of moving up and down to the base of an audio signal
will be attractive to night-club owners.
3. Technical Specifications
3.1 Levitation
The Levitating LED Light will be a 2-3 inch diameter plastic sphere, floating in a
magnetic field, which will oscillate vertically to the bass notes of music. The levitation will be 23 inches below the control box, which will house the control circuitry for levitation as well as the
inductive AC coil. The reader should note, from Figure 2, the two distinct parts of the project,
the controller and the orb.
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Figure 2. Orb and controller with
dimension A and B, undermined,
dimesions C and D are 2-3 inches.
The control box, shown in Figure 3, will house two magnetic coils (levitation and
inductive), the DC power converter, the control circuit, and the Hall-Effect (HE) sensors. The
levitation coil will be a 4 inch diameter, 50 turn coil made from 18 AWG magnetic wire. The
levitation coil will be responsible for repelling the orb, and should provide 8 Gauss of peak
repulsion force at 2 inches. The amount of repulsion will be controlled by the current through the
coil. Figure 4 demonstrates how the DC Bias is set by feedback from the HE sensors and the bass
filter.
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Figure 3. Control box with control circuit, AC coil,
levitation coil, Hall Effect sensors, and AC power input.
Figure 4. Control circuit with the levitation coil controlled
by the HE sensors and the bass filter.
Figure 5. Orb with induction coil, magnet, and LEDs.
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The orb, shown in Figure 5, will enclose the receiving induction coil, and the
Neodymium magnet, and the six LEDs will be on the outside. The weight of the orb is crucial for
levitation, since the pull force of the magnet must be matched with the downward force from the
weight of the ball. Table 1 shows an estimated weight calculation for the orb.
Table 1. The Components and Estimated Weight of the Orb
Item
LEDs
Levitation Coil
Plastic Ball
Magnet
Calculation
0.1 grams (x 6)
0.339 (grams/ft.) * 16 ft.
10 grams
163 grams
Total
Total
0.6 grams
5.42 grams
10 grams
163 grams
179.02 grams
The Neodymium magnet selected for the project is capable of attracting to the control
box with 180 grams of force at a distance of 2 inches. The magnet, with dimensions 1.5 inches
diameter and .75 inches height, weighs 163 grams. Figure 6 shows the Gauss rating of the
magnet as a function of distance, and highlights the point 1.5 inches away, providing .51 lbs of
upward force.
Figure 6. Force (lbs) vs. Distance (in)
for the Neodymium magnet.
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3.2 Wireless Induction and Audio Oscillation
The LEDs will be powered by a wireless induction circuit, which receives power from
the induction coil in the controller. The time-varying flux from the AC coil above will induce a
current in the induction coil. The AC coil in the controller will be 10 inches in diameter and less
than 2 inches in height. It will be made of approximately 100 turns of 14 AWG magnetic wire.
Once the controller achieves balance, oscillation will begin in time with the bass notes of
the music. The music will be interfaced from a music device, such as an mp3 Player, lap top, or
other audio player, through a 1/8” audio jack located on the control box. The circuit located in
the controller box will filter the input to remove the bass notes. The circuit will oscillate the orb
by varying the DC bias point in the levitation coil.
4. Design Approach and Details
4.1 Design Approach
The L3 will be designed in three phases: the levitation phase, the wireless power transfer
phase, and the vertical displacement phase. The final product, depicted in Figure 1 has the
Neodymium magnet in the top of the orb is attracted to the iron core in the electromagnet (or any
other metal chosen to encase the orb in). The levitation electromagnet creates a magnetic field
that opposes this attraction, thus creating an air gap between the orb and the electromagnet.
Using readings from the two Hall Effect sensors, the strength of the electromagnet is constantly
adjusted though a feedback control system. The control system will allow the L3 to avoid the
constraints stated in Earnshaw's Theorem and achieve stable magnetic levitation. A high
frequency sinusoidal signal of approximately 100 kHz will be super-imposed on to the DC
current in the coil of the electromagnet. This time varying current creates a time varying
magnetic field which is used to induce current in the coil located in the orb. The coil in the orb is
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connected in parallel with a capacitor and four light-emitting diodes (LEDs). The capacitor is
chosen such that the parallel combination of it and the orb’s coil is resonant at the frequency of
the aforementioned super-imposed sinusoid. This reduces the reactance of the circuit and allows
maximum power to be transferred to the LEDs. Finally, a third control segment is implemented
which filters an iPod's audio output signal and creates the control signal for the vertical
displacement function. This control signal is appropriately scaled and summed into the coil
current which increases the repulsive force of the electromagnet and forces the orb to lower for
the duration of the bass note.
The levitation phase consists of implementing a mounting stand, an AC/DC converter, a
levitation electromagnet, Hall Effect sensors for the control system, and the floating orb (minus
the LEDs since they cannot be tested at this time). The stand, depicted in Figure 7, will be
constructed from non-magnetic materials such as PVC or wood and epoxy.
Figure 8. Levitation
Figure 7. Stand for control box.
electromagnet with dimensions,
flux, and current direction.
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The Sunforce 11230 AC/DC Power Converter was chosen as the AC/DC power converter
since it is capable of providing more than enough power for the coil current. It produces 69.6 W
of power at 5.8 A of current. In the event that the power delivered by the converter is either
excessive, or too unstable, a smaller power supply will be selected.
The levitation electromagnet will be constructed by wrapping MagnaWire around a
cylindrical piece of iron. The number of wrappings will be maximized in order to produce as
much flux as possible and is a function of the length of the bar and the gauge of the wire.
Preliminary calculations show that a tall core with small radius yields the most flux. The initial
test unit will be approximately 8 cm tall and 0.5 cm in radius. These dimensions may be adjusted
as testing is conducted in order to provide maximum field strength and control. A diagram
depicting the levitation electromagnet with dimensions, flux, and current directions is provided
in Figure 8.
The Hall Effect sensor of the control system, in Figure 4, will measure the magnitude of
the magnetic field on either side of the levitation coil. The field at these two points is
proportional to the distance the neodymium magnet is from the levitation electromagnet. The
sensor information is processes and used to make coil current adjustments in order to maintain
stable levitation. The MLX90215 sensors by Melexis Inc. were chosen since they have analog
outputs and high sensitivities. If the Hall Effect sensors are negatively affected by the time
varying fields, then the distance sensor will be changed to a passive analog IR distance sensor.
The wireless power transfer phase adds a separate power transfer coil around the
levitation coil, a power receiving coil to the floating orb, and circuit components to the control
circuit and floating orb. The floating orb consists of a polymer sphere attached to the neodymium
magnet with weight or extra wire added to simulate the payload to be added in future design
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iterations. Levitation and power transfer require two different coil designs to achieve maximum
efficiency as illustrated in Figure 3.
A high frequency, approximately 100 kHz, sinusoidal oscillator will be designed or
purchased to provide the power signal. This signal will be amplified and routed to the power
transfer coil. The 100 kHz frequency was selected as a balance point. As frequency increases, the
amount of power transferred increases, but so do losses in the coil due to the skin effect. This
frequency is subject to change if another one is found to work better through experimentation.
The power transfer coil will be a 0.5-2 inch tall, 8-12 inch diameter coil of wire oriented
perpendicular to the ground and around the outside of the levitation coil. This configuration
causes it to act as a multiple turn loop antenna.
The power receiving coil will be added around the inner radius of the floating orb,
perpendicular to the ground. This orientation yields maximum loop area, which maximizes
received power. A capacitor will be connected in parallel with the coil with its size chosen such
that the receiver circuit is resonant at the transmission frequency. This lowers the impedance of
the receiver and maximizes the power transferred. The LEDs will then be connected in parallel
as the only load on the receiving coil. The LEDs will blink 100,000 times per second, which is
not visible to the human eye.
The vertical displacement phase will require a high order Chebyshev or elliptic filter, a
headphone jack, and control electronics. An audio signal is input through the headphone jack
from an iPod or other mp3 music device. The filter is used to remove all the non-bass
components of the audio signal. This is then processed and used to vary the coil current causing
vertical displacement to the beat of the music.
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4.2 Codes and Standards
To power the L3 a standard 2-prong 120 VAC wall plug will be utilized. The IPOD
interface will be a standard 3.5 mm audio input jack. The adapter is well documented and
commonly used for transferring audio signals. The L3 wiring will be routed through the plastic
support stand, eliminating the possibility of faulty wiring and/or ground fault currents causing
injury. Finally, there will be a kill button to cut power to the device to allow swift reaction to
unforeseen circumstances.
4.3 Constraints, Alternatives, and Tradeoffs
The Neodymium magnet must be selected such that its lift to weight ratio at 2-3 inches is
greater than one. The magnets strength, size, and weight all increase together. The lifting power
of the magnet decreases exponentially with distance from the plate it is attracted to as shown in
Figure 6.
The wire gauge of the power receiving coil will be chosen such that the AC resistance
and weight will be minimized, while the number of turns is maximized. Weight decreases as the
wire gauge increases, however thinner wire increases the AC resistance. Thinner wire also
allows more turns, increasing the transferred power.
5. Schedules, Tasks, and Milestones
The L3 device will be designed, implemented, and demonstrated in the next three months.
Table 2 shows the major tasks in bold and the successful milestones in italics.
After the completion of the Levitation, the LED Illumination and Vertical Motion tasks
will overlap. This is because the AC power input needs to sufficient for both and the circuitry
designs will be required to be integrated with one another.
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Table 2 - Schedule of Tasks and Milestones
Task Name
CALCULATIONS
Power Requirements
Design Targets
LEVITATION
Levitation
LED ILLUMINATION
Wireless Power Transfer
LED Illumination
Optimization
VERTICAL MOTION
Feedback Controls
Sinusoidal Filtering
Orb Momentum and
Balancing
DEMONSTRATION
Demonstration
FINAL PRESENTATION
Duration
4 Days
0 Days
0 Days
30 Days
0 Days
17 Days
0 Days
Start
09/22/10
09/25/10
09/27/10
09/27/10
10/24/10
10/28/10
10/24/10
End
09/27/10
09/25/10
09/27/10
10/28/10
10/24/10
11/22/10
10/24/10
0 Days
22 Days
0 Days
0 Days
10/29/10
10/28/10
11/07/10
11/14/10
10/29/10
11/22/10
11/07/10
11/14/10
0 Days
3 Days
0 Days
0 Days
11/22/10
11/29/10
12/03/10
12/06/10
11/22/10
12/03/10
12/03/10
12/06/10
The detailed schedule in Appendix A includes the team leaders for each major tasks as
well as the members responsible for the minor tasks associated. The project will be completed
one week prior to the demonstration in order to be fully prepared and allow time for
troubleshooting. A Gantt chart is also available in Appendix A.
6. Project Demonstration
The final project will be an L3 prototype and will be demonstrated in a classroom in the
Van Leer Building at the Georgia Institute of Technology. The performance testing of the L3 will
be conducted in three phases.
The first phase will test the ability to levitate the light fixture. This will be accomplished
by first plugging the L3 into a 120 VAC electrical outlet and switching it on. A student will then
place the light fixture in the magnetic field and release it as the controller stabilizes it. Next, the
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student will wave their hand, or other non-magnetic material, between the light fixture and the
electromagnet to prove levitation. Also at this time, the student will use a wooden ruler to
measure the distance from the bottom of the electromagnet to the top of the light fixture, which is
the levitation distance.
The second phase will begin by first turning of or dimming the lights in the classroom.
Next, the student flip will the switch located on the base of the L3 to turn on the lights. Once the
L3 lights up, the student will again wave their hand, or other non-magnetic material, between the
light fixture and the electromagnet to prove wireless transmission of power.
The third phase will first have the student plug the audio output of a music listening
device (mp3 player, laptop, etc.) that is playing Enter Sandman by Metallica into a splitter. The
audio from the music player will be split into two signals: one going to the audio input jack on
the L3 and the other going to a pair of speakers.
7. Marketing and Cost Analysis
7.1 Marketing Analysis
The L3’s target markets are individuals and businesses that play music. Bars, pubs, and
night clubs looking to differentiate themselves from their peers can install an overhead L3
variation. The music-reactive lighting adds additional entertainment dynamic, thus attracting
additional customers. Individuals looking to enhance their own musical experience, or entertain
at parties can also utilize the L3 in a similar way, but on a smaller scale.
The Fascinations Corporation and sells a variety magnetically levitating globes which
also spin in place. They range from $40 for a 4 inch, non-rotating globe to $100 for an 8 inch
rotating model. The L3 distinguishes itself by providing light as well as dancing to music.
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7.2 Cost Analysis
The total estimated cost for the L^3 prototype is $46,083. All materials can be procured
for approximately $100, and the labor cost is approximately $36,792. Since many of the required
materials are either cheaper, or can only be purchased, in bulk quantities, it may be possible to
produce more than one prototype. Table 3 illustrates the material cost breakdown of the L3.
Table 3. Material Cost Breakdown of the L3
Product Description
Iron Core
Magna-Wire 80’ spool
Op-Amps, LEDs, Transistors
Hall Effect Sensors
AC/DC Power Converter
Headphone Signal Splitter
1/8 inch Female Headphone Jack
Neodymium Magnets
PVC Stand
Total Cost
Quantity
1
1
25
2
1
1
1
1
1
Unit Price ($)
3
30
.2
5
30
3
1
5
20
Price ($)
3
30
5
10
30
3
1
5
20
93
According to http://www.bls.gov/k12/math02.htm, the labor costs are calculated using an
hourly average labor rate of $42/hour; 99.8 percent of the project’s cost is in labor which is
shown in Table 4.
Table 4. Total Project Projected Costs
Project Component
Class
Levitation
Controls
Power Transfer
Documentation
Total Labor
Total Parts
Total Overhead
Total Project
Labor Hours
120
132
132
132
360
876
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Labor Cost
5040
5544
5544
5544
15120
36,792
Material Cost
37
56
(with controls)
5
Total Section Cost
5040
5581
5600
5544
15120
93
9198
46083
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8. Summary
Presently we are researching previous implementations of similar devices. We are also
looking for high power op amps and transistors as well as analog distance sensors and Hall
Effect transducers. We are preparing to order the parts needed to implement the levitation
portion of the project. Parts for the rest will be ordered as soon as specifics parts have been
decided on.
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9. References
[1] Coil Gun. (2008). Other Maglev [Online]. Available:
http://www.coilgun.info/levitation/other_maglev.htm [Accessed: September 18,
2010]
[2] http://gizmodo.com/317135/crealev-floating-lamp-leavens-any-room [Accessed:
September 18, 2010]
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Appendix A: Gantt Chart
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