Xem 1-8 trên 8 kết quả Light an led
  • First off, it’s all about the lumens. Lumens are the visible light given off by a source, and they are the ultimate goal. Wattage has often been confused with lumens, thanks to how incandescent bulbs are rated (everyone knows that a 60W bulb is not as bright as a 100W one), but more efficient lighting technologies have greatly changed the relationship between wattage (essentially power usage) and lumens (light output). For example, an incandescent might operate at about 12-15 lumens-per-watt (lm/W), while an LED bulb will be in the range of 40-50, a much greater luminous efficacy...

    pdf69p aries23 29-09-2012 62 30   Download

  • The MintDuino is deceiving—this little tin of electronics is capable of providing the brains for an unlimited number of devices limited only by your imagination… and, of course, your bank account. While the MintDuino is certainly capable of being used during a moment of inspiration, you’ll find that the real power of the device comes when you sit down, figure out what you want to make, and then start tackling your project a bit at a time.

    pdf58p hotmoingay3 09-01-2013 14 2   Download

  • Serial Connection And Parallel Connection Figure 1 shows the most basic and commonly used circuits for driving light-emitting diodes. In Figure 1(A), a constant voltage source (VCC ) is connected through a current limiting resistor (R) to an LED so that it is supplied with forward current (IF). The IF current flowing through the LED is expressed as IF = (V CC - VF)/R, providing a radiant flux proportional to the IF. The forward voltage (V F) of the LED is dependent on the value of IF, but it is approximated by a constant voltage when setting R. Figures 1(B) and...

    pdf44p lehieukutek 26-12-2009 95 11   Download

  • Build a robot that responds to electrical activity in your brain—it’s easy and fun. If you’re familiar with Arduino and have basic mechanical building skills, this book will show you how to construct a robot that plays sounds, blinks lights, and reacts to signals from an affordable electroencephalography (EEG) headband. Concentrate and the robot will move. Focus more and it will go faster. Let your mind wander and the robot will slow down. You’ll find complete instructions for building a simple robot chassis with servos, wheels, sensors, LEDs, and a speaker.

    pdf96p lock_123 08-04-2013 43 16   Download

  • Optical Fibers The phenomenon of total internal reflection, responsible for guiding of light in optical fibers, has been known since 1854 [1]. Although glass fibers were made in the 1920s [2]–[4], their use became practical only in the 1950s, when the use of a cladding layer led to considerable improvement in their guiding characteristics [5]–[7]. Before 1970, optical fibers were used mainly for medical imaging over short distances [8]. Their use for communication purposes was considered impractical because of high losses (∼ 1000 dB/km).

    pdf54p khinhkha 29-07-2010 40 7   Download

  • Optical Transmitters The role of the optical transmitter is to convert an electrical input signal into the corresponding optical signal and then launch it into the optical fiber serving as a communication channel. The major component of optical transmitters is an optical source. Fiber-optic communication systems often use semiconductor optical sources such as light-emitting diodes (LEDs) and semiconductor lasers because of several inherent advantages offered by them.

    pdf56p khinhkha 29-07-2010 56 7   Download

  • To our knowledge, only one previous effort (Wilson et al, 2007) explicitly studied school travel in light of school choice. There, we found that school choice led to longer school commute distances (because children attend schools across the district rather than in their neighborhood) and reduced levels of walking and bicycling to school (because longer commutes are less amenable to walking or bicycling). The current study strengthens and expands earlier research.We survey parents to determine attitudes that affect school choice and school travel mode.

    pdf0p nhacnenzingme 23-03-2013 16 3   Download

  • In a similar vein, Azuri Technologies has focused its attention on African villages that are too remote to have any connection to an electric power grid. Azuri’s technology uses solar cells and the latest lithium battery technology to run two powerful LED lights for up to eight hours, eliminating the need for expensive kerosene lamps. What makes Azuri unique is its business model. Instead of selling the system, Azuri leases it at a cost that even poor villagers can afford. The basic equipment is available for a nominal fee, and the customer then leases time on it by purchasing...

    pdf77p doiroimavanchuadc 19-02-2013 28 2   Download

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