The L.E.D. Close-Up.

When a small current flows through an L.E.D. (normally
about 20-30 milliamps) it will light up. Unlike an ordinary bulb,
its two connections ( + and -) must be connected correctly to
the power source for it to work.

Standard L.E.D.
Symbol

 

 

The two different connections to the L.E.D. are :

1, The Anode (+)

2, The Cathode (-).

These can be identified by looking for either the long (+) or
short (-) legs. The flattened edge of the led is always nearest
to the Cathode (-). Please look carefully at the image above
to see this.

 

Getting it working

L.E.D.s are semiconductors and most of them cannot work
safely in a circuit on their own. This is because they allow too
much current to flow - unlike the light bulb that takes only the
current it needs to work.

To protect the L.E.D., it is necessary to use an electronic
component called a resistor. This is connected in series
with it.

Please go on to the next link to find out about this.