DESMA 256 - Actuators
(compiled by Aaron Siegel)

Motion Motors: - Direct Drive - Gearhead - Stepper - Servo - Vibrator - Solenoid - Piezoelectric Shape Memory Alloys: - Thermal - Ferromagnetic Electroconvulsion: - Living Muscle Tissue

Light Bulbs: - Incandescent - Halogen - Cold Cathode - Neon - Fluorescent - Metal Halide - Sodium Discharge Semiconductors: - Light Emitting Diode (LED) - Organic LED - Electroluminescent Wire - Lasers

Sound Electromagnetic: - Speaker Piezoelectric: - Transducer

Thermal Joule Heating: - Ceramic Heating Element - Metal Heating Element Peltier Cooling: - Thermoelectric Cooler

Switch Relays: - Reed - Solid State Transistors: - BJT - FET Vacuum Tubes: - Tubes

Motion
Motors:

	Direct Drive Direct drive motors are comprised of a magnet and series of copper coils, which when an electrical current is run through them create an electromagnetic field causing the rotor to spin. These motors can be brushed or brushless. Brushes are used to maintain an electrical contact from the outside (stator) to the inside (rotor) which is where the electromagnetic coils are wound. Brushless motors require a controller since they do not contain commutators. Direct drive motors are identical in design to generators, so if rotation is applied to the rotor a voltage can be produced. Retailers: - Jameco: $0.85 - $7.19 - All Electronics: $0.80 - $26.00
	Gearhead Gearhead motors are similar in their construction to DC motors except that they contain an additional casing that utilizes a gear ratio system to adjust the torque output. --> Photo of a dissasembled gearhead motor. Retailers: - Jameco: $14.95 - $25.35 - Digikey: $46.55 - All Electronics: $4.50 - $19.25
	Stepper Stepper motors are brushless motors that utilize pulses of electricity to turn a fraction at a time. The rotor consists of a metal gear which is surrounded by toothed electro-magnets on the stator. Stepper motors require a controller to adjust the movement. Because of their resolution of movement, they are ideal in moderately precise applications. --> Illustrations of stepper motor. Retailers (motor): - Jameco: $1.35 - $178.15 - Digikey - All Electronics: $1.00 - $15.35 Retailers (controller): - Jameco: $147.25 - $247.99 - Digikey: $82.40 - All Electronics: $25.00
	Servo Servo motors are even higher precision than stepper motors. The servo motor consists of a brushed DC motor (or AC motor) and the resolver/encoder. The resolver/encoder is a small glass disk with very fine lines, and an photocell that counts the lines as the rotate with the stator. This data is sent back to the servo controller to analyze the current speed and make any adjustments. Servo controllers are able to track the movement of their servo mechanisms. Retailers (motor): - Jameco: $16.95 - $179.95 Retailers (controller): - Jameco: $39.95 - $271.79
	Vibrator These motors are often simply direct drive DC motors with an offset weight affixed to the stator. This causes the center of gravity of the motor to fluctuate rapidly when spinning and causes a vibration that fluctuates according to voltage and amperage applied. Often referred to as pager motors, they can be made very, very small. Retailers: - Jameco: $2.35 - $6.49 - All Electronics: $1.25
	Solenoid A solenoid motor is a linear motion device that can push or pull a rod between the stator coil. Applications include remote triggering of switches or chimes (analog doorbell). Retailers: - Jameco: $7.35 - $31.39 - Digikey: $21.00 - $35.00 - All Electronics: $1.25 - $9.70
	Piezoelectric Piezeoelectric motors are driven by ultrasonic vibrations created from the piezoelectric transducer. They are not very commonly produced, but can be made incredibly tiny.

Shape Memory Alloys:

Thermal Two name brands, flexinol and nitinol, are the most commonly available shape memory alloys created from nickel and titanium. When a current is driven through them, the principles of joule heating warms the metal wire causing it to contract. The material quickly loses heat when no longer carrying a current, and relaxes back to its original shape. The material is available as untrained wire spools or as pre-trained springs good for linear motion applications. --> A document on training nitinol. Retailers: - Jameco: $15.95 - $248.95

Ferromagnetic Ferrofluid is comprised of nanoscale ferromagnetic particles suspended in a carrier fluid. The particles react to electromagnetic fields and changes the shape and reaction of the fluid. Retailers: - Forcefield Magnets: $25.00

Electroconvulsion:

Living Muscle Tissue Living muscle tissue can be actuated to contract when an electrical current is run through it. I asked my friend carlos castellanos who specializes in biological art: "You can't induce a muscle spasm on a preserved/dead animal beacuse the cells no longer have any pottasium & calcium, and thus have no electrical potential. I suppose with enough voltage you can make it move but that's really just force not really a spasm, but i guess it doest matter as long as you dont fry it! "Your best bet (and I was almost able to do this) is to get recently pithed frogs from a lab that just finished using them that day and explant the fresh muscle. It will still have some charge and you can make it twitch with just a little voltage, or take the whole frog and apply voltage to the sciatic nerve, which will twitch the whole leg." Commercially available electrical muscle stimulators have been around for decades, used to exercise or massage muscles.

Light
Bulbs:

	Incandescent Incandescent light bulbs are the oldest form of electrical lighting, and having changed very little since their invention over a century ago, are incredibly inefficient. 95% of their energy draw is emitted as heat rather than visible light. Good for easy bake ovens, bad for illumination. Lumens per Watt: 6 - 20 Color Range: 2000 - 6000K Retailers: - Home Depot - OSH - Walmart
	Halogen Halogen bulbs are actually a type of incandescent bulb that has been filled with halogen gas and utilizes a tungsten filament to last longer and burn at higher temperatures. It is slightly more efficient, where 9% of their energy consumption is output as visible light. Lumens per Watt: 16-24 Color Range: 2200 - 3400K Retailers: - Home Depot - OSH
	Neon Neon signs consist of enclosed tubes that contain neon gas, which when an electrical current is passed through glows orange-red. Other colors are produced using fluorescent tubes and various colored phosphorous coatings. Lumens per Watt: ? Color Range: Neon Orange Retailers: - Jameco: $0.33 - $66.95
	Cold Cathode A cathode is an electrode that emits electrons. Most fluorescent lighting uses hot cathodes, but cold cathode tubes do not require the cathode electrode to be heated to produce thermionic emission of electrons. They are most conventionally used as decorative lighting in computers and cars, as well as used in combination with diffusers to act as backlighting for LCD displays. Cold cathodes utilize a ballast to stabilize current flow. Lumens per Watt: ? Color Range: visible spectrum + ultraviolet Retailers: - All Electronics: $5.35 - $15.00
	Fluorescent An electrical current is used to excite mercury vapor which produces shortwave ultraviolet light. The UV rays bombard a phosphorescent coating on the inside of the tube causing it to glow and emit visible light (as well as shield UV rays from escaping the tube). Blacklights function in the same way, but instead use a europium-doped phosphor that blocks as much visible light as possible and allows UV rays to pass through. Flourescent's also use ballasts. Lumens per Watt: 45 - 104 Color Range: 3000 - 6500K Retailers: - Home Depot - OSH - Walmart
	Metal Halide Metal halide lamps can contain specialized mixtures to create color temperatures between very yellow and very blue. They are most often implemented in industrial settings, security lamps, LCD projectors, and indoor plant cultivation. Lumens per Watt: 65 - 115 Color Range: 3000 - 20000K Retailers: - Home Depot - OSH
	Sodium Discharge High and low pressure sodium lamps are incredibly efficient, incredibly powerful lights, often ranging between 50 - 1000 watts per bulb. They are used in street lights, security lights, and indoor plant cultivation. --> Image of an HPS lamp spectrum. Lumens per Watt: 150 - 200 Color Range: 2500K Retailers: - Home Depot: $100 - $400 - OSH: $100 - $400

Semiconductors:

	Light Emitting Diode LED's are made of semiconductor materials that produce an electroluminescent effect when a charge is sent in one direction through them. A narrow wavelength of photons is emitted according to the properties of the material used. Lumens per Watt: 18 - 150 Color Range: Infrared to almost Ultraviolet Retailers: - Jameco: $0.04 - $3.75 - All Electronics: $0.10 - $11.50
	Organic Light Emitting Diode The future. Printable. Flexible. Self Illuminating. Transparent. Unfortunately low-lifespan especially on blue OLED's which prevents them from taking over the LCD display market. Currently implemented in low-resolution tiny displays for phones and mp3 players. Research is being done on replacing organic material with an electroluminescent polymer. Retailers: - Digikey: $7.60 - $31.30
	Electroluminescent Wire A thin copper wire coated in an electroluminescent phosphor which is then wrapped with a very fine copper wire and it is all insulated in a pvc tube. The electrical charge between the two wires illuminates the phosphor material. Another sleeve of translucent colored pvc is wrapped around that to give the wire the desired hue. Used in computer enclosure and car modding. Retailers: - All Electronics: (flat strips) $1.00 - $9.95 - VibeLights: $1.15 - $1.25 per foot.
	Lasers A single wavelength of photons emitted in a coherent beam. Available in red (common), green (rare), or infrared (expensive). Retailers: - Jameco: $14.95 - $49.95 - Digikey: $5.37 - $136.90

Sound
Electromagnetic:

Speaker Speakers work similarly to solenoid motors in that they produce linear motion to actuate the air and cause sound waves to travel. Its construction consists of a large magnet around the outside (the stator) and a coil of copper wire known as the voice coil in the middle. A current is applied to the coil which creates an electromagnetic field, interacting with the magnetic field of the solid magnet and pushing or pulling against it accordingly. Speakers are designed for certain frequency range responses, seperating their output into categories; subwoofer (20 - 100hz), woofer (40 - 2000hz), and tweeter (2000 - 20000hz). In the same way direct drive motors can be used as generators, the voice coil on the speaker can be vibrated to produce a voltage (how most microphones work). Retailers: - Jameco: $1.39 - $2.89 - All Electronics: $0.50 - $39.95 - Digikey: $3.23 - $19.91

Piezoelectric:

Piezo Transducer Piezo's are made of a crystalline material that produces a voltage when vibrated or vibrates when a voltage is applied to it. Piezo's have a limited frequency response, but require very little power and are ideal for embedding in tiny places (like hallmark cards). Retailers: - Jameco: $1.25 - $16.79 - All Electronics: $0.75 - $1.00

Thermal
Joule Heating:

	Ceramic Heating Element Ceramics with a positive thermal coefficient are used as heating elements because they act as self regulating thermostats. Current passes through the material when it is cool and does not when it is hot. Used most commonly in terrariums with cold blooded pets. Retailers: - Electric Heating Association: $28.75 - $52.75
	Metallic Heating Element Most metallic heating elements use nichrome wire or ribbon as a conductor because it has a high resistance and does not oxidize in the air. The wire can be coiled into a spring shape and encased in a harder metal tube such as the heating elements used in soldering irons. Retailers: - Jameco: $20.95 - Electric Heating Association

Peltier Cooling:

Thermoelectric Cooler The peltier effect is the creation of a heat difference between two different types of metals from an electric voltage. The direction of heat transfer is controlled by flow of current, in effect creating a thermoelectric heat pump system for redistributing heat. Has become quite common for cooling in the CPU overclocking community, on satellites to redistribute heat from direct sunlight around the craft, and to keep your guiness cold. Retailers: - All Electronics: $9.75 - $14.75

Switch
Relays:

Reed Reed relays can be actuated in two ways: magnetically and electromagnetically. The simple principle is that there is a tiny metal wire inside the relay tube which clicks together and makes contact when influenced by a magnetic field. This is commonly used in window alarm systems. They also make a really attractive clicking sound when they change states. Most commonly used for switching low voltage. Retailers: - Jameco: $1.15 - $44.75 - All Electronics: $0.75 - $1.00 - Digikey: $1.59 - $30.93

Solid State Solid state relays contain no moving parts, and are thus less susceptible to wear than reed relays. They are also faster since no motion is required to activate the switch. Commonly used for controlling high voltage switching with a low voltage source. Retailers: - Jameco: $3.49 - $44.39 - All Electronics: $4.50 - $10.50 - Digikey: $0.88 - $95.55

Transistors:

Bipolar Junction Transistor Transistors are used as digital switches, allowing current to pass through when electrons are detected on a trigger channel. Transistors have three pins: emitter, base, and collector, which have different uses depending on the type of bipolar transistor in use. The two different types are PNP and NPN, referring to the majority charge carriers the semiconductor layers are doped with. NPN transistors allow current to pass from the collector to the emitter only when there is a current applied to the base pin. PNP transistors allow current to pass from the emitter to the collector when the base pin does NOT have a current applied to it. Retailers: - Jameco: $0.05 - $8.55 - All Electronics: $0.10 - $2.00 - Digikey

Field Effect Transistor FETs have four pins: the gate, drain, source, and base. FETs are used in two main ways: enhancement, in which a voltage applied to the gate increases current flow from source to drain, or depletion, in which a voltage applied decreases the current flow from source to drain. This makes them convenient for use as automated variable resistors in analog circuits. Retailers: - Jameco: $0.15 - $1.69 - All Electronics: $0.10 - $2.00 - Digikey

Vacuum Tubes:

Vacuum Tubes Diode tubes are simply a cathode filament and anode plate inside a glass bulb. When hot, the filament releases negatively charged electrons into the vacuum. The electrons are drawn to the anode because it is positively charged, thus creating a one way current. Triode tubes have an additional piece called the grid, which is a simple wire screen placed in between the cathode and anode to which a varying voltage is applied, thus controlling the amount of electron flow from the cathode to the anode. The closest solid state ancestor of the triode vacuum tube are JFETs.