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Light-emitting diode

A light-emitting diode (LED) is a semiconductor light source.[3] LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic component in 1962,[4] early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs are often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern.[5] LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output. Light-emitting diodes are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting, and traffic signals. LEDs have allowed new text, video displays, live video, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.

A particle carrying a charge of 1 coulomb and passing through a magnetic field of 1 tesla at a speed of 1 meter per second perpendicular to said field experiences a force of 1 newton, according to the Lorentz force law. As an SI derived unit, the tesla can also be expressed as (in SI base units).[3] Units used: A = ampere C = coulomb kg = kilogram m = meter N = newton s = second T = tesla V = volt Wb = weber [edit] Electric vs Magnetic Field

The difference between magnetic field strength (in tesla) vs electric field strength can be confusing.[citation needed] The difference is that a force of magnetic field on a charged particle is generally due to the charged particle's movement[4] while the force imparted by an electric field on a charged particle is not due to the charged particle's movement. This can be seen by looking at the units for each. Electric field is N/C, while magnetic field (in tesla) can be written as N/(C*m/s). The difference between the two is m/s, or velocity. This can further be seen by noting that whether a field is magnetic or electric is dependent on one's relativistic reference frame (that is: one's velocity relative to the field).[5][6] In ferromagnets the movement creating the magnetic field is the electron spin[7] (and to a lesser extent electron orbital angular momentum). In current carrying wire (electromagnets) the movement is due to electrons moving through the wire (whether the wire's straight or circular).

The 620325 Stirling Engine by Thames and Kosmos uses renewable energy from the sun to drive a generator, which charges a rechargeable battery to power an electric car.

Power a Car with Solar Generated Electricity       Discover the Stirling engine, a simple, clean and efficient energy technology that is quickly becoming a viable source of electricity as the availability of fossil fuels declines. The Stirling engine in this kit uses renewable energy from the sun to drive a generator, which charges a rechargeable battery to power an electric car. Named after its inventor, Robert Stirling, the original Stirling engine dates back almost 200 years. Today, high-tech Stirling engines are being used in arrays of giant mirrored solar collectors and common applications like compact generators. NASA is even working on using Stirling engines to power a human outpost on the moon!Like a steam engine, a Stirling engine is a heat engine that converts heat energy into mechanical work, usually to drive a generator that then converts the mechanical energy into electricity. But instead of water and steam, the Stirling engine uses a permanently enclosed volume of gas, such as air or helium, to perform the mechanical work. Stirling engines are highly efficient, can operate very quietly, and can use many different sources of heat: combustion of fuels, nuclear fission, geothermal, or solar heat, as this model uses. The Stirling engine in this kit is located in acharging station with a mirrored parabolic dish. The dish focuses the sun’s rays onto the cylindrical glass bulb of the Stirling engine to heat it up. The air inside the bulb heats up and pushes a piston, which turns an electric generator. The generator produces electricity that charges a rechargeable battery in the car. The car runs on an electric motor powered by the battery.The kit includes the charging station with a beta type Stirling engine, the electric car, and a full-color, 64-page manual.

The U49325 Sun Runner Stirling Engine is a solar-powered Stirling Engine which offers a dramatic demonstration of energy conversion.   This motor and its parabolic mirror can be attached to any conventional camera tripod. When properly aimed at the sun, the polished aluminum parabolic mirror focuses incoming solar energy on the heat cap of the engine, which is converted to rotary motion. Unit comes complete with motor, parabolic mirror, and wrenches. Standard camera tripod is not supplied. This engine is completely assembled and ready to run. Each unit is test run at the factory prior to shipping. Motor runs at 2,000 RPM and up. This engine can also run as a horizontal engine with an alcohol burner. Demonstrate this exciting method of harnessing the sun’s clean and renewable energy to your students.  Weight: 6.00 lbs Dimensions: Engine: 8.25 x 3 inches (L x W) Flywheel: 3.25 inchesParabolic Mirror: 18 inch diameterPlease note that this item is designed to demonstrate the operating principles of a Stirling engine for educational use and is not designed for power production.  It can potentially be coupled with a generator for producing very small amounts of electricity but is incapable of powering anything beyond a small light bulb or LED.

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CrazyFlie flight video

The copter itself is organised around the main CPU. The job of this CPU is to acquire the physical measurement given by the gyroscopes and accelerometers and to control the motors to keep the copter stable. This is done by a regulation loop which controls the motors speed 250 times per second. The radio communication has a pretty low bandwidth and is used to send commands to the copter and receive telemetry data from it. The CPU program can be updated by radio.

The computer runs control and telemetry programs. The control program reads the input from a game-pad and sends control commands to the copter. We also have programs that can configure the copter regulation parameters and log the measurements in order to make easier to tune the regulation. All the development is done on Windows and Linux. Indeed we are 3 to work on this project, two of us work on Linux and one is mainly on Windows. Using FLOSS permit to handle that in a very effective way. We are mainly using the GCC compiler from CodeSourcery for the copter program compilation, GNU Make for the project build, Mercurial for the source control, and python/pyusb for the communication with the copter. All these softwares works seamlessly on both Linux and Windows and made the project pretty easy to handle. The distance between the motors (horizontally and vertically) is around 8 cm and the total weight is around 20 g.

Z-Wave is a wireless communications protocol designed for home automation, specifically to remotely control applications in residential and light commercial environments. The technology uses a low-power RF radio embedded or retrofitted into home electronics devices and systems, such as lighting, home access control, entertainment systems and household appliances.

What is CryptoParty? Interested parties with computers and the desire to learn to use the most basic crypto programs. CryptoParties are free to attend and are commercially non-aligned. Privacy is necessary for an open society in the electronic age. Privacy is not secrecy. A private matter is something one doesn't want the whole world to know, but a secret matter is something one doesn't want anybody to know. Privacy is the power to selectively reveal oneself to the world.

$49.99

BELKIN Belkin WeMo Home Automation

Turn electronics on or off — from anywhere. Operates over Wi-Fi and mobile internet, at home and away. You’ve already got everything you need: WeMo works with your existing Wi-Fi router and any iPod touch, iPhone, iPad - iOS 5 or higher. Put your electronic devices on a schedule. Modular system. You can add additional WeMo Switches easily, any time. Control as much or as little of your home as you want to.