We made many references to Light Emitting Diodes (LEDs) in this book and many readers are interested in LEDs. They can serve both decorative and functional purposes. LEDs are diodes that light up as the name suggests. Diodes are two-terminal, one-way electricity controls. Current is allowed to flow only in one direction. The important characteristics of LEDs are as follows:
They have a minimum voltage before they can turn on. This voltage will vary slightly with the amount of current flowing through it. Different LEDs will have different voltages. This is determined by the underlying physics of the LED. On a datasheet, this is often labeled as the forward voltage.
As an LED is a diode which conducts only in one direction, the polarity at which an LED is hooked up matters. The terminals on an LED are the anode and the cathode. The anode should go to the positive side of the power source.
The brightness of the LEDs is determined by the current through them. An...