3.2.3. BCD to 7-segement decoder experiment

Components:

• breadboard
• 5V power supply
• common cathode 7 segment display
• 4 x SPST pushbutton switches
• 4 x 2.2KΩ resistors
• 7448 BCD to 7-segment decoder chip with configuration:
  • Pin 14 as VCC, Pin 7 as ground
  • the rest is self-explanatory from the schematic

Figure 3‑10 BCD to 7-segment decoder schematic

Figure 3‑11 BCD to 7-segment decoder circuit

Explanation: The input pins 3, 4, and 5 of the U1 7448 chip are not used, hence are connected to a positive voltage source. Also, the decimal point input of the U2 7-segment display is not used, so it remains unconnected. The final thing to mention is that, since we are using a common cathode 7-segment display, we must ground one or both CC (common cathode) inputs.

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