User manual

1.5 Light Emitter Diodes

The LED (light emitting diode) has another property in addition to those of a

regular diode: It lights up when voltage is applied. LEDs should usually always

be operated with a dropping resistor for current limitation. Red LEDs require the

lowest voltage (1.8 V). Then there are yellow, green, blue and last white LEDs with

the highest voltage (up to 3.6 V).

a) b)

Fig. 006: a) Connection assignments of the light-

emitting diodes: the anode (+) with longer connection

wire (left) and the cathode (–), b) additionally marked

by a attening at the housing. c) The circuit symbol

of the LED

In addition to the »normal« LEDs, there are also special versions such as a

ashing LED. The ashing LED can be recognised by the small black drop within

the red housing. This dot contains tiny electronics in the form of an integrated

circuit that makes the LED ash - once the right voltage is applied.