ABSTRACT
The current through an LED must generally be limited by wiring a resistor in series with it (p. 15).
The brightness of an LED is specified in candela (cd) or millicandela (med). Typical LEDs are in the range 6-10 med. Super-bright LEDs have brightnesses of tens or even hundreds of millicandela, while the brightest types are rated' at up to 30 candela. Viewing angle is also important, for some types achieve high brightness by concentrating the light into a narrow beam. This makes them less conspicuous in a display if the viewer is not directly in front of the panel. Standard LEDs have a viewing angle of 120°, but the angle may be as small as 8° in some of the brighter types.
