Flashlight Buying Guide

<p>Gone are the days when buying a flashlight meant one would automatically seek out Maglite. Whilst recognising the impact and unprecedented success of the Maglite design, LED, HID (High Intensity Discharge) and Xenon technology along with ultra strong casing materials means that the flashlight has evolved to a state where the more powerful the beam does not necessarily mean the larger the flashlight.</p>

<p>When seeking out high performance, reasonably priced lighting tools it is easy to become swamped by the amount of brands on the market. Flashlight technology at the beginning of the 21st century offers a baffling variation of bulb type, body material, body size, power source and price range. This guide is a brief overview of the salient points worth consideration when buying any quality flashlight. </p>

<p>In the same way that feet measure length so lumens measure brightness. The higher the Lumen count the brighter and further the beam will show. Occasionally you may find brightness levels measured in Candlepower or Candelas, this describes a unit of light at source. One Candlepower/Candela is equal to 12.57 Lumens.</p>

<p>Perhaps the most significant breakthrough in lighting technology was the L.E.D. (Light Emitting Diode). The L.E.D. produces light on a molecular level as distinct from a normal bulb, which heats a filament therefore using more energy to produce less light. As a result an L.E.D. will last a lifetime and dramatically lengthen the life of a battery. They do, however, vary in purity. Like diamonds, at the point of production some produce clean white light whereas others have a very slight blue, violet or green tint.</p>

<p>Xenon Lights produce a broad spectrum of light (including infrared) and can be made to have a high maximum lumen output by the inclusion of Xenon gas in the bulb thus enabling light to be produced at a higher pressure, but they are comparatively less efficient users of power. H.I.D technology (High Intensity Discharge) uses a Xenon bulb slightly differently with the addition of a tubular outer bulb and an inner arc tube with a cerium-doped quartz partition in the bulb to block out most ultraviolet. HID torches have lumen output of approximately 500-1000. Lighting technology could be described as a battle between light and heat, as the energy to produce the heat detracts from that which produces the light.  The undoubted master is the LED. It makes light without the need to heat a filament, thus lengthening bulb and battery life. However the power from a Xenon bulb can be astoundingly bright yet harder on the batteries.</p>

<p>Casing material has progressed so far as to be almost indestructible if dropped and virtually water resistant in very wet conditions. A good, quality flashlight will invariably have an Aerospace grade aluminium body and a rugged construction and design. </p>

<p>Manufacturers vary in quality and specialism. Surefire have a quality range of Xenon and LEDs with a comprehensive range of accessories. Ledwave produce excellent, powerful and reasonably priced LED and Xenon lights. Nextorch can boast the extraordinary Saint, capable of producing a massive 450 lumens, plus a range of    ingeniously, versatile LED, Xenon and rechargeable torches.</p>
<p>Navigating the labyrinth of flashlight production is tricky and ultimately dependant on what job will be asked of it. Lumen output to size ratio, tough hardwearing casing material and bulb / battery life are essential elements to take into consideration when choosing a lighting tool to last and perform over time.</p>

Consumer Electronics Items

Introduction:

The daily use of electronic equipments are known as consumer electronics and includes TV, telephone, DVD, CD, PC, laptop etc. These equipments are manufactured throughout the world. With the advancement in electronic engineering at a continuous pace, a number of new variety electronics items flood into the market every year and the cost the existing products reduces continuously and it is one of the biggest advantage of consumer electronics industry.

Electronic waste is one of the problems associated with these electronic item and many manufacturers are now planning to deal with these waste.

Semiconductor:

All electronic devices use semiconductors and without these semiconductors none of the electronic device is complete. Semiconductor behaves like an insulator at absolute zero (-273 degree centigrade) and can be distinguished from conductor that at this temperature the outermost filled electron energy band is completely filled in a semiconductor compare to the conductor in which the band is partially filled.

At room temperature semiconductor show a very small electrical conductivity much lower than that of conductor.

Doping in semiconductor:

Most common semiconductors used for electronic devices are silicon and germanium. Although some other conductors such as iridium phosphide, gallium arsenide and mercury cadmium telluride are also used.

A pure semiconductor also known as intrinsic semiconductor, when doped with electron rich element e.g. arsenic or electron deficient element e.g. boron in very small quantity, its conductivity increases and the resultant conductor is known as extrinsic conductor. My doping arsenic (electron rich) and boron (electron deficient) in silicon, we get n-type (negative type) and p-type (positive type) semiconductor devices.

We may create a p-n junction by doping different element in different region of semiconductor and the device is known as diode. Similarly we can create p-n-p or n-p-n junctions and the device is known as triodes.

Electronic Devices

(a)    Television:
It is a device by which we can receive moving pictures and sounds over a distance. The whole transmission and receiver systems require the following inputs.
1.Camera for live images or flying spot scanner for transmission of films and sound source.

2.Transmitters for transmitting both images and sounds.

3.Receiver systems for receiving these signals.

4.Display device, which is either CRT, Rear projection, LCD or plasma. To display the signal in the forms of images and sounds.

(b)    Telephone:

It is the device for communicating by which two persons can send and receive sound signals over a distance. The system requires the following inputs.

1.The telephone equipment, which converts sound signals to electrical signals and electrical signals to sound signals.

2.Central exchange from where the subscribers are interconnected.

3.Wiring for connecting all the subscribers.

(c)    Calculators:

It is a device used for carry out various mathematical calculations. The input required for calculator are as given below.

1.Power source (battery or solar panel).

2.Display device (LED or LCD)

3.Keypad containing all functions and numbers.

4.All electronic circuit devices.

Electronic Waste:

These are the waste electronic devices and if properly utilized may be valuable secondary raw material source for various electronic equipments and if thrown out may act as toxic due to presence of various toxic materials including lead, mercury, cadmium, arsenic etc. uncontrolled burning of these materials may also cause environmental problems.

Electronic waste is sometimes illegally sent to other countries for processing. However, due to complexity and difficulties in recycling, e-waste will remain an issue for the coming days.