Presentation of the leds
    Since the previous century, lighting occupies a place impossible to circumvent in our company. That generates great energy needs.

Moreover, with regard to lighting in him even, it always does not require the same sources of light. That is the direct consequence owing to the fact that any system of lighting has particular characteristics. Thus, for each precise use and according to the constraints (of temperature, of pressure, of output, size or of lifespan) the selected source is different.

The led, because of its characteristics, is a judicious choice in a great number of situations.

It should be noted that it is common that the word "led" is put in the plural.
Example: I bought leds this morning to make a small assembly or there is a led which flickers .
    The electroluminescent diode is a rather recent invention. Indeed it is into 1962 that the first electroluminescent diode with visible spectrum was created by Nick Holonyak
It should be noted that the LED emitting in will infra red are older (they are often used in the remote controls).
 


Cross of a led

 ●Lentille (colored case)
It makes it possible to protect the LED


●Reflecting Coupelle
It makes it possible to direct the luminous rays in a precise direction.


●Puce semi conducting
It emits the light and measures approximately 1 mm 2


●Contacts of food (the long leg symbolizes it -)
It allows the connection of the LED the electric assembly

●Fil of bonding (very fine)
   
    A led is characterized by various physical sizes
  - Vs:La tension of threshold: tension from which photons are emitted.
- λ:longuor of emitted wave.
- Vr: maximum opposite tension
 

At first sight the case of a led has a symmetry of revolution around its central axis. But it of it is nothing! The led has a edge in bottom of the lens (coloured case) but not around: beside there or the leg of the anode is inserted this edge does not exist. There is a notch. The sight "top" opposite will light you.

This notch is not there to make pretty. Indeed, when a led already was montée/démontée much, the legs are twisted even crossed and it is not easy to see which is longest.
Moreover, with the notch, the recognition of the anode and cathode is possible in all the situations (even when the led is welded).