Chapter 7
Lights, LEDs, and Power
Mandala Project by Justin Campaniello, 2012
Photocopied drawings, foamcore, light bulbs, Super Cricket microcontroller
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Lights have many different uses in an Artbotics project: an illuminated light tells you whether your
work is turned on; they can be used to illuminate a specific area; and they can function aesthetically as
part of the piece. The context in which the lights are used gives them meaning, so it is important to reflect
on how they are utilized within a piece. Lights convey information via color, brightness, and how they are
turned on and off. Lights can blink, can vary their brightness while turned on, and can convey movement
and animation through patterns. They can signify light itself or stand as a metaphor for something else.
Lights can be programmed to be brighter or dimmer based on power usage; they can be indicators of
scientific or electronic values, like whether or not another sensor has been activated or a connection has
been closed; and they can serve purely decorative ends. This chapter will consider these properties and
how to work with them in your piece.
7.1 What is a light bulb? What is an LED?
A light bulb is a vacuum sealed glass globe with a wire in it that glows when heated up by
electricity. It was invented in 1879 by Thomas Edison and is now being phased out as they cost more to
run than LEDs and compact fluorescents. Light-Emitting Diodes, more commonly known as LEDs,
were invented in 1962. LEDs use a semiconductor, a chunk of material that conducts electricity under
some conditions but not others, that emits light when electricity is applied to it. The main difference
between a light bulb and an LED is how they are powered: LEDs have a specific orientation in which they
must be connected, while light bulbs do not.
Light bulbs and LEDs need an electric source to light them up. They can be powered by batteries
(also known as direct current power, or DC) or by “wall outlet” electrical power (alternating current, or
AC). All electric power sources have a positive (power) and a negative (or ground) circuit orientation. In
these early chapters, we will work only with batteries because direct current is safer for learning and
experimentation. In Chapter 17, we will talk about how to work with plug-in wall power (AC) for powering
parts of your piece by using relays and how to power your entire piece using wall power. Alternating
current, which comes out of wall outlets, can electrocute a person when used incorrectly.
A battery is a chemical source of electricity. On the battery, the positive side has a plus (+) on it
and the negative side has a minus (-); it matters which way you orient these in the battery case. If you
install a battery the wrong way, your project may not work. Worse, there is a chance that the battery
could leak acid or “blow up,” which is less dramatic than it sounds, but creates a hazard and damages
your electronics.
Figure 7.1 shows a AA battery, 2 wires, and a light bulb in its accompanying socket. If one were
to screw the bulb into the socket, connect one end of each wire to a tab on the socket, and press the
other end of each wire against one side of the battery, the bulb would light up, regardless of the positive
and negative orientation.
For an LED, however, you must use the correct positive and negative orientation or the LED will
not work. In figure 7.2 the long LED lead (both leads look like a pin coming out of the bulb) is called an
anode. The anode must touch the positive side of the battery, while the short lead, called a cathode,
must touch the negative side. Try this and watch the LED light up.
However, if your battery had too much power for your LED, that may be the last time you see
your LED light up. It is possible to burn out LEDs by using too high of a voltage. You should be sure to
buy LEDs that match the voltage that your microcontroller outputs. (You can use other LEDs. See
Chapter 17 for a discussion of how to use resistors to use lower power LEDs with your piece.)
Most of the micro-controllers we will use in these projects are powered by 5 volts. Generally, the
microcontrollers have enough extra power for a small light bulb or LED. However, if a light bulb needs
more energy than what the microcontroller has available to share, we must use an external power source
and a relay switch to power the light bulb. Relays will be covered later in Chapter 17.
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7.2 Power: Volts, Watts, Ohms, and Amps
Volts, watts and ohms are used for measuring electricity and are named after the scientists
James Watt, Alessandro Volta, and Georg Ohm. A Volt (V) is a measure of “electromotive force” or
pressure and it is what generates electron flow. It is more than we can go into here, but, simply put, a volt
is the difference in electrostatic charge between two points. This imbalance between two points is what
causes electrons to want to flow from one area to another, like the two different ends, or poles, of a
battery. This electron flow we perceive as electricity. Visualize a shaken up soda bottle. The potential
force of liquid that will spill out when you open the bottle is your voltage.
An Ohm denotes the resistance to electric current an item has. All electric parts have some
resistance and in a circuit you need to supply enough power to overcome the accumulated resistance of
the parts. Even humans have some electrical resistance, about 1000 ohms () depending on body fat and
moisture. Sensitive bits of electrical equipment in a circuit sometimes need to be sheltered from the
available electricity coming in by other bits called resistors. These look like globs of silicone on a wire and
they soak up electrons and so add resistance to the circuit. Power versus resistance comes into play for
the typical non engineering consumer when you are hooking up stereo speakers: too much power will
damage the speaker and too much resistance will prevent any sound from coming through.
A Watt (W) is a measure of electricity and you see it on items that use electricity, like appliances,
telling the consumer essentially how much it will cost in home power usage to run the appliance. A watt
represents one ampere of energy per second. An Ampere (amp, denoted with an “I” below) measures
electric current: one amp is the amount of current produced by a force of one volt acting through the
resistance of one ohm.
Here is the formula for it, called Ohm’s Law: I = V/R. Current (I) equals voltage (V) divided by
resistance () . You might need it later to calculate whether you have enough power in your circuit to
support a high number of light bulbs or speakers.
How do you find out how much power your light needs? Read the technical specifications for the
LED model you have, which can often be found online if you look up the part number. You can also test
any electrical part with an electrical voltage tester. Read the section on how to use a multimeter at the
end of this chapter.
Please refer to the Manufacturer’s Manual for information on a specific microcontrollers output
voltage.
Figure 7.1
The relationship between positive and negative (the polarity) does not matter for powering a light bulb.
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Figure 7.2
The longer lead, or the anode, must touch the positive, while the short lead, or the cathode, must touch the
negative. If this relationship is reversed the LED will not power on and could potentially become damaged.
7.3 Example projects using lights
Girl with Broken Heart (figure 7.3) by Alyssa
McCann, 2011, uses colors emotively: red is the color
of a heart, there are eyeballs with green pupils, and
yellow is used to convey excitement. There is an
eyeball light that animates the eye opening and closing
(even though the actual eyelids, which are a printed
magazine image, do not physically move) and the
heart light turns on and off in a syncopated rhythm to
imply a heart beat. The yellow light turns on very
brightly and quickly after the eye and heart have run
their sequence, emphasizing the explosive lines
nearby. Here, the lights are used to aid a narrative by
lighting up in a sequence. When the lights are on in a
certain area, the viewer is drawn to look there, then
when they turn off and another light comes on, the
viewer’s focus shifts to the new area. The code used to
sequence lights will be explored more in Chapter 8.
Lights can also be used to emphasize form
and pattern. See figure 7.4 for Geometric Cityscape by
Samantha Weeden, 2011. The three cylinders that
contain light bulbs light up at the same time, then
slowly dim until they are all dark. The shape of paper
tubes directs the light towards the surface openings,
like a flashlight. Every other “building” is a rectangle
tube. Unlike Girl with Broken Heart, here the lights are
being used to highlight pattern and to metaphorically
suggest city lights.
Figure 7.3
Girl with Broken Heart by Alyssa McCann, 2011,
collaged printed magazines, light bulbs, Super
Cricket microcontroller. Photo by Adam Norton
In this piece there are three lights: a green light in
the top eyeball, a red light in the broken heart, and a
yellow light at the explosion lines next to the girl’s
head.
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Figure 7.4
Geometric Cityscape by Samantha Weeden, 2011, paper, light bulbs, Super Cricket microcontroller.
Photo by Adam Norton. In this piece there are three lights (red, green, and yellow) each placed in a
cylinder shape.
What is the message of a light bulb?
What is the message of a light bulb? This question was considered by Marshall McLuhan in
Understanding Media, 1964. McLuhan’s big idea was that technology milestones in themselves conveyed a social
message and that had meaning in addition to whatever messages those technologies were being employed to
accomplish. His first example is the electric light. We might think of the electric light as something that can be used
to say things when, say, those messages are words lit up in electric lights, like “Eat Here” or “Now Showing”. We
might even understand that an electric red light at an intersection is a sign for stop. This, McLuhan says, misses
the point. The point of an electric light is all the stuff we can do now that we could never do before electric lights
were invented. Think about how the electric light has made nighttime human activity possible, from night baseball
to bedtime reading to industrial mining and third shift at the factory. These activities, and the extension of all
human activities into dark spaces enabled by the electric light, is the message of the electric light.
In contemporary media, light always signifies intelligence, ideas, clarity, cognition. The most famous light
bulb belongs to the robot Hal from 2001, A Space Odyssey, directed in 1968 by Stanley Kubrick. Hal controls the
space capsule the humans are taking for their quest to find intelligent life on other planets and it has decided that
the human’s best interests are not necessarily its own. In the film he is signified by his voice and by a blinking red
light. This red light reappears in WALL-E by Pixar in 2008 as Auto, the robot controlling the destiny of the Axiom
and all surviving human life. What other famous robots can you think of use a light to indicate they are alive?
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7.4 Soldering
Soldering is the fusing of two metal objects
with a low melting point metal alloy. The soldering iron
supplies heat to the two metal parts and that heat
melts the solder. Once the joint is cool, it creates a
strong electrical connection, and is useful on circuit
boards, wires, and many other electronic devices.
When using a light bulb or LED in an Artbotics
project one does not attach it directly to a battery; it
must be soldered to its corresponding wires and/or
appropriate connectors. The required tools and
materials for soldering are: a soldering iron, solder,
two or more wires (for our exercise, just two), heat
shrink tubing (available any store selling these other
things), and either a bulb & socket or an LED.
About Solder
Solder is made up of tin, lead, and sometimes silver,
zinc, or antimony. Lead can leach through your skin,
is toxic to breathe, and when eaten, is a neurotoxin
that compromises brain functioning and
development. It is toxic to fetuses and to small
children when ingested. It hangs around in the body
for a long time and so has a cumulative pathogenic
effect. It is also great for soldering electrical parts
together because it melts fast and makes strong
joints. If you are pregnant, you must use a respirator
when handling lead solder or working in the same
room with others who are using it. You can switch to
lead-free silver solder, which is a bit more expensive.
It is more challenging to work with but the health
benefits are worth it. Either way, wash your hands
before you eat or touch your face or use the
bathroom. Lead toxicity in the body can be mitigated
through a high iron and high vitamin C diet.
7.4.1 How to solder two wires together:
1. Plug in and turn on your soldering iron.
2. The wires that are to be soldered must first be stripped about ⅓ of an inch to expose the
conductive metal wires beneath the outer plastic casing. If using heat shrink tubing to encase the
new joint, it must be placed over the stripped wires before soldering.
3. If using solder flux, apply it now. Some solder already has flux in it, check your package. Flux
keeps the wires clean and free of oxidation so that they solder easier.
4. Pre-tin each bare wire: heat up the wire by holding the soldering iron to it and add a bit of solder
to the wire. when the solder turns to liquid and coats the wire, remove the iron. If you have a third
arm clip, put the wires in it while soldering to keep from burning your fingers.
5. Twist together the two bare connector wires.
6. Apply the soldering iron to the wires. The secret to soldering is that both wires need to be the
same temperature, and as hot as the iron, to get the solder to flow. If one wire is too cold, it won’t
work, so apply the heat evenly. Larger items need more heat than smaller items.
7. The molten solder will be shiny when liquid and dull when hardened. It hardens in a matter of
seconds after you remove the heat.
8. Test your joint by gently tugging on it to see if it breaks. If not, you are done.
9. If using heat shrink tubing, slide the tubing over the exposed joint BEFORE you solder, and use a
lighter or a heat gun to melt the tubing onto the joint.
For soldering a light bulb and socket see figure 7.5. For soldering an LED see figure 7.6.
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Figure 7.5
When soldering a light bulb strip one end of two wires. Wrap the stripped end through and around the tab on the socket.
Solder over the connection until the entire tab is filled with solder. Heat shrink is not necessary for a light bulb as the two
wires have no way of crossing. Remember, in a light bulb the power polarity does not matter.
Figure 7.6
When soldering an LED strip one end of two wires. Take two pieces of heat shrink and place them over the wires. Make
sure to note which end is positive (longer lead, anode) and which end is negative (shorter lead, cathode), then wrap the
stripped wire around each lead. Cover the connected wires and leads in solder, then place the heat shrink over the
connection. Apply heat using a heat gun until they shrink over the connection.
7.4.2 Extending Wires
The manufactured pre-cut wires that are attached to lights and motors are often not long enough,
especially for a larger project. For example, if a light bulb must be placed 18 inches from a
microcontroller, but the supplied wire is only 6 inches, then the wires must be extended by adding more
wire. To do so, one must cut the wires that are currently soldered on and add a length of wire in between.
See figure 7.7.
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Figure 7.7
The white wire is going to be extended with the length of the gray wire. Cut the white wire and strip each cut end. Also strip
each end of the gray wire. Slide two pieces of heat shrink over the wires, then twist each stripped end of the white wire to
one end of the gray wire. Cover the twisted wires in solder, then place the heat shrink over the connections. Apply heat
using a heat gun until they shrink over the connections.
7.4.3 Non-solder connectors
Some examples of non-solder connectors.
There are many products in electronics that will make a good electrical connection without using
solder. There are twist cap connectors, barrel connectors, push in connectors, crimps, male and female
couplers. (see image above). The main thing to remember is that these connectors need to match your
wire diameter size. A too large connector will not hold the wires together and a two small one may
overheat and melt.
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7.4.4 Connecting to your Microcontroller
Now that your lights are soldered and ready to be used, they must be connected to your
microcontroller. Electronic parts connect differently for each model of microcontroller; some use the two
wires and connect directly into the microcontroller, while others have custom 2 pin connectors that the
wires plug into before connecting to the microcontroller. Be sure to study the manual that comes with your
microcontroller.
For instance, the Super Cricket microcontroller has 4 ports, labelled A, B,C, and D, for
connecting lights, LEDs, and motors. Each port has a sister port, allowing a second component to be
plugged in and controlled using the same port letter. Each port has 2 prongs, which correspond to the 2
wires that are used to power a light or LED. There are also specially crimped wires that connect into
small, plastic housings that plug into these ports. The other ends of these wires connect to the light or
LED. One wire is the positive (power) and the other is the negative (ground), and as discussed earlier for
a light bulb the orientation of these wires does not matter, but for an LED the anode must connect to the
positive and the cathode must connect to the negative. Before soldering these wires to the LED, you will
have to program your Cricket to turn on the port you are plugging into and test to see what orientation will
work.
Super Cricket connectors
The Super Cricket microcontroller uses a 2-prong housing connector for lights and DC motors. It has other 3 and 4-prong
connectors for sensors and expansion boards.
Arduino microcontrollers have positive and negative digital pins for attaching components, and
some have connectors similar to the Cricket. The Arduino LilyPad uses conductive thread to attach from
the microcontroller to LEDs. The Lego Mindstorms NXT microcontroller uses connectors similar to a
telephone plug. For a full detailed list with more information go to http://www.artbotics.org/
7.5 Series vs. Parallel Circuits
A set of components connected by wires is a circuit and the wires are the pathway the electricity
travels on. If you need to power multiple lights with one power supply, then you will chain the lights
together in a circuit like in a strand of Christmas lights. Many different components can be linked together
to feed off of one power source: motors, speakers, and sensors. There are two types of circuits: parallel
and series.
A series circuit offers only one path for the electricity to follow from power supply to
component and back again. Visually, it looks like a circle shaped train track. It’s called a series circuit
because the electrons move to each element in the order they are wired. (See figure 7.8.) As more lights
are added to the series chain the amount of electricity that flows through each one is diminished, making
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all of the lights less bright. Each light bulb represents a
load on the total available power, and that load adds up. A load
is an item in an electrical circuit that draws or uses electricity:
your dishwasher, television, and refrigerator all add up to a total
load on your household circuit. If there are too many items
demanding power, your circuit will overheat and shut down. In
our diagram 7.3A, if one bulb is unscrewed from its socket then
the rest of the lights will not work. This is because each light
serves as a necessary bridge in the circuit.
In a parallel circuit, the electricity has more than one
path it can travel. In figure 7.9, four lights each have their own
power and ground wires connected to the main power and
ground wires. This disperses power to each light so if one light
breaks or is removed the other lights are not affected. A parallel
circuit needs to balance the voltage demands and resistance
presented to the power supply. Each component offers
resistance (Ohms) to the flow of electrons in the circuit. If one
branch of the circuit has less resistance, the electrons will prefer
that path and potentially burn out the component on that path.
We use parallel circuits when we want redundancy in a
system: to prevent failure of multiple components if one burns
out. We use parallel when we are dividing up the resistance
load of a set of speakers or lights on a system so as to feed
each component an equivalent amount of power. And we use
parallel circuits if there is only one power supply but there are
multiple types of circuits to be powered: for example if you have
a speaker and a light that are triggered by different events but
share the same power supply.
Figure 7.8
Soldering in series: As more lights are
added to the chain, the available power for
each light is reduced.
Figure 7.9
Soldering in parallel
The four light bulbs here share the same power (positive) and ground (negative) sources from the connector.
Each light has an equally distributed amount of power, and they all shine at the same brightness.
These wiring methods are very useful in an Artbotics project because the number of individual
power output connections a microcontroller has is generally between 2 and 8, and some connections may
need to be used for components other than lights. Each output port is individually controlled by the
microcontroller. if four separate lights are plugged into four different ports on a microcontroller then they
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can each be controlled uniquely. However, if a chain of four lights is plugged into one port on a
microcontroller then it must be thought of as a single light. Power sent to that chain will turn all of the
lights on or off simultaneously. In addition, a microcontroller can adjust the power made available to the
light or output port and so cause the light to dim on command or lower the amount of power available to
the object attached to the port.
In Geometric Cityscape (figure 7.4), all three lights turn on and lower in brightness at the same
time. All three lights can either be wired as a series circuit and controlled as a single light, or each light
can be wired individually and controlled simultaneously. Girl with Broken Heart (figure 7.3) has its lights
on different circuits. If all three lights were on a single chain, then the heart, eyes, and explosion light
would have to turn on and off together. The piece would lose its complexity and dynamic narrative. For
this piece to function properly each light must be individually controlled.
A much larger project, City of Lights by Kristen Dubis, 2011, figure 7.10, uses more than 50 lights.
There are 6 different chains of lights, each chain is soldered in parallel, and they are controlled via
different output ports, and so highlight different windows in different buildings. Here, soldering in series
would not have worked because the flow of power would diminish very quickly given the entire load of
lights in each chain. Throughout the life of this piece some light bulbs did burn out or get damaged, but
because they were soldered in parallel instead of series all of the other lights were unaffected. The piece
is controlled by two Super Cricket microcontrollers which output 5 volts each. Even when soldered in
parallel more than 50 lights could not be powered by only 5 volts, so an external power supply was
brought in to generate an additional 12 volts of power.
Figure 7.10
City of Lights by Kristen Dubis, 2011, wood, paint, light bulbs, Super Cricket microcontrollers
Photos by Holly Yanco. This piece contains more than 50 lights. There are 6 different chains of lights, wired in parallel,
which turn on and off.
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2-D Artbotics Pattern Project - Part 2
Adding lights to your mandala collage.
In this lab, you will add 3 lights to your 2-D art that you
constructed for Chapter 6. By using a
light sensor or a touch sensor (or both), you will make
your project interactive. Materials needed: microcontroller,
light bulbs, light sockets, light sensor, touch sensor,
cricket display, your 2D art.
1.
2.
3.
4.
5.
6.
7.
8.
Solder a wire to the tab on one side of the light
socket and another wire to the other.
Put the loose ends of the wire into the two-hole
solderless white cricket connector. The wires
should snap into the connector. If you can pull
them out easily, turn the connector around 180
degrees and insert the wire again.
Determine the location for your light socket in
your artwork.
Cut or drill the necessary hole and install the
socket. Then screw in a light bulb.
Repeat until you have three wired light sockets
inserted in your artwork.
Consider where you will mount your
microcontroller. To the back of the art? To work it
must be embedded in the art somewhere. How
will it stay attached? Velcro? Nuts and bolts? Zip
ties?
Attach the wires from the lights to the correct
output ports on your microcontroller. Are they
long enough to reach? if not, extend them as
described earlier in this chapter.
Write a cricket logo program to create interesting
light patterns (see Chapter 8).
Example mandala collage projects
Projects (top to bottom) by Jessica Tawczynski and
Renee Lantz, 2012.
Further Reading
 Getting Started in Electronics by Forrest M. Mims III (Paperback - Feb 2003), Master Publishing,
Inc.
 Introduction to Electricity, NDT Resource Center. http://www.ndted.org/EducationResources/HighSchool/Electricity/electricityintro.htm
 Understanding Media by Marshall McLuhan, Magraw-Hill; 5th Printing edition (1966)
Some electronics supply outlets
 Sparkfun: http://www.sparkfun.com/
 Nelco: http://www.nelcoproducts.com/
 Jameco: http://www.jameco.com/ElectronicComponents
 American Science and Surplus: http://www.sciplus.com/
 Radioshack: http://www.radioshack.com/
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
All Electronics: http://www.allelectronics.com/
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