3-28
uses seven LED segments, or bars (labeled A through G in the figure), which can be lit in different
combinations to form any number from "0" through "9." The schematic, view A, shows a common-anode
display. All anodes in a display are internally connected. When a negative voltage is applied to the proper
cathodes, a number is formed. For example, if negative voltage is applied to all cathodes except that of
LED "E," the number "9" is produced, as shown in view A of figure 3-29. If the negative voltage is
changed and applied to all cathodes except LED "B," the number "9" changes to "6" as shown in view B.
Figure 3-28A.—Seven-segment LED display.
Figure 3-28B.—Seven-segment LED display.
