A combinational logic circuit for traffic control is designed. ___________ GATE can only be used to implement the designed control circuit without any additional GATES.

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HPCL Engineer Instrumentation 11 Aug 2021 Official Paper
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  1. NOT
  2. EXOR
  3. AND
  4. NAND

Answer (Detailed Solution Below)

Option 4 : NAND
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Detailed Solution

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The logic gate for traffic control is:

Input J Input K Red Light X Yellow Light Y Green Light Z
0 0 1 0 0
0 1 1 1 0
1 0 0 0 1
1 1 0 1 0

For red light

Output X = NOT (J)

For yellow light

Output Y = K

For green light:

Output Z = J AND (NOT K)

Combined Circuit is given as,

Now, all the gates can be formed from NAND gate, as it is a universal gate. 

NAND gate will be the correct answer. 

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