About Light Emitting Diodes

Light emitting diodes, (commonly called L.E.D.s), are really unsung heroes in the electronics world. They have dozens of various uses and are found in all kinds of devices. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.

A diode is a very simple semiconductor device that allows electricity to flow in just one direction. If you apply current in that direction (called forward-biasing), the diode produces light as a side effect. For ordinary diodes, that light is infrared, invisible to the naked eye. By varying the materials used in the diodes, scientists were able to produce diodes that made visible light—red at first, and later, other colours. The physics behind Light emitting diodes dictates that whatever light is produced is of a single wavelength (that is, a single colour). But for a long time, nobody could figure out how to make colours with shorter wavelengths than green. A researcher at Nichia Chemical Industries in Japan - Shuji Nakamura thought he had determined just the right type of material (indium gallium nitride, if you care) to use for blue LEDs. The problem was that the existing manufacturing processes did not produce material of sufficient quality. So he had to invent a new process as well. In 1993, Nakamura finally produced the first commercially viable blue LEDs. This achievement alone would have earned Nakamura a place in electronics history. But the real genius was in his next step. He applied a special type of phosphorescent coating to a blue LED. The blue light excited the molecules in the coating and produced bright white light, so white LEDs are actually a clever spin-off of blue LEDs.

Advantages of using Light Emitting Diodes

• Colour Changing
  L.E.D.s can emit light of an intended colour without the use of colour filters that traditional lighting methods require. This is more efficient and can lower initial costs.
  
• Energy Efficient:
  • The key strength of L.E.D. lighting systems is in their low power consumption and durability. On average L.E.D. based lighting systems will use 60%-70% of the power consumption of their incandescent counterparts.
  • While lower power consumption reduces operating costs, it also reduces wear on other components in the application such as transformers, batteries and power converters.
  • LEDs produce somewhat more light per Watt than incandescent bulbs.
    
• Durable and hard wearing
  • L.E.D.s are built inside solid cases that protect them, unlike incandescent and discharge sources, making them extremely durable.
  • The solid package of an L.E.D. can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a useable manner.

• Long Life
  • L.E.D.s have an extremely long life span: the operational life of current white L.E.D. lamps is 100,000 hours. This is 11 years of continuous operation, or 22 years of 50% operation, approx twice as long as the best fluorescent bulbs and twenty times longer than the best incandescent bulbs, which is approximately 5000 hours.
  • Further, L.E.D.s fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.
  • L.E.D.s light up very quickly. An illumination L.E.D. will achieve full brightness in approximately 0.01 seconds, 10 times faster than an incandescent light bulb (0.1 second), and many times faster than a compact fluorescent lamp, which starts to come on after 0.5 seconds or 1 second, but does not achieve full brightness for 30 seconds or more. A typical red indicator L.E.D. will achieve full brightness in microseconds, or possibly less if it's used for communication devices.
    
• Low heat emission
  • L.E.D.s give off much less heat than incandescent light bulbs with similar light output.

IP Rating explained:

The IP (Ingress Protection) standard is a system for classifying the degrees of protection provided by enclosures of electrical equipment, e.g. a bathroom light fitting rated IP65 means that it is totally protected against dust and gives protection against water jets and water projected by a nozzle from any direction.

FIRST NUMERAL

PROTECTION AGAINST HUMAN ACCESS OR SOLID OBJECTS

0 no protection

1 Protected against solid objects with a diameter of 50mm and over (e.g. accidental insertion of hands)

2 Protected against solid objects over 12mm (e.g. jointed fingers)

3 Protected against solid objects over 2.5mm (tools)

4 Protected against solid objects over 1mm (small wires)

5 Protected against dust - limited ingress permitted (no harmful deposit)

6 Totally protected against dust

SECOND NUMERAL

PROTECTION AGAINST HARMFUL INGRESS OF LIQUIDS

0 no protection

1 Protected against drops of condensed water.

2 Protected against drops of liquid.

3 Protection against rain.

4 Protection against splashing.

5 Protection against water jets.

6 Protection against conditions on ship decks. Water from heavy seas etc.

7 Protection against immersion in water. It shall not be possible for water to enter the enclosure under stated conditions of pressure and time

8 Protection against indefinite immersion in water under specified pressure. It shall not be possible for water to enter the enclosure.