■ FIGURE 1. Schematic.
the unregulated voltage from DB1. Jumper JP1 allows the
user to configure the thermometer to display either
Centigrade or Fahrenheit temperatures.
The jumbo thermometer uses three large seven-segment LED displays. In this circuit, the seven segments
of all three displays are bussed together. Each display digit
can be selected by an output from the CD4017 decade
counter U3. This configuration allows any digit to be
addressed by the microprocessor using a technique called
multiplexing.
■ FIGURE 2. Parts Placement.
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