2.6.1. XOR gate experiment

Components:

• breadboard
• 5V power supply
• 5mm red LED
• 2 x SPST pushbutton switches
• 220Ω, 2 x 2.2KΩ resistors
• 7400 NAND, 7432 OR, 7408 AND chips with the same configuration:
  • Pin 14 as VCC, Pin 7 as ground
  • Pin 13 A input, Pin 12 as B input
  • Pin 11 as output

Figure 2‑20 TTL chips realization of NOR gate

Explanation: The circuit is self-explanatory according to the explanations of OR, NAND and AND gates.

We can further use a 7486 chip containing four XOR gates, organized according to the figure below.

Figure 2‑21 Chip 7486

Finally, we are missing only the last of the basic logic gates – the XNOR gate. With all this experience, it is very easy to understand that all this gate does is invert the output of the XOR gate. Hence, the XNOR Boolean operation for A and B operands is expressed as follows:

Therefore, the output of the XNOR gate is 1, only if both inputs are the same. The same applies to multiple operands. The implementation of the experiment is left as an exercise to the reader.

Back

Contents

Forward