Logic Game Using Digital Logic Gates


Introduction: Logic Game Using Digital Logic Gates

Logic gates are an important concept if you are studying electronics. These are important digital devices that are mainly based on the Boolean function. Logic gates are used to carry out logical operations on single or multiple binary inputs and give one binary output. In simple terms, logic gates are the electronic circuits in a digital system.

The logic gates that we are going to use in this project are:

  • AND gate
  • OR gate
  • NOT gate

AND Gate

In AND gate the output of an AND gate attains the state 1 if and only if all the inputs are in state 1.

If A=1 & B=1 then the output will be 1 otherwise, it will be zero

OR Gate

In OR gate the output of an OR gate attains the state 1 if one or more inputs attain the state 1.

If A=0 & B=1, the output will be 1 or

A=1 & B=0, the output will be 1 and

A=1 & B=1, the output will be 1

NOT Gate

The NOT gate has only one input. In NOT gate the output of a NOT gate attains the state 1 if and only if the input does not attain the state 1.

If A=0 the output will be 1 or

A=1 the output will be 0

Logic Game working

The working of this game is pretty straight forward. There are 8 switches with the help of which we have to make a specific combination to turn ON a LED. Eight switches means 256 combinations(2^8=256).

Once the LED is turned ON then we have to turn OFF the LED with the same 8 switches we used to turn the LED ON. Again there are 256 combinations out of which just 1 combination will turn OFF the LED.

There are total 512 combinations in which 2 combinations are used to turn ON and OFF the LED. More switches you add the more combinations you can make which is 2^n (n is the no. of switches).

To hold the ON state of the LED I used S-latch that uses 2-OR and 2-NOT gates.

The logic game schematic using Logic gates and logic IC's is also provided so you can check it out....


  1. OR gate IC (74LS32) x 2
  2. AND gate IC (74LS08) x 3
  3. NOT gate IC (74LS04) x 1
  4. Vero board x 1
  5. Soldering Iron x 1
  6. Soldering wire x 1
  7. LED's x 9
  8. 330 ohm resistors x 9
  9. 10k ohm resistors x 8
  10. Wire cutter x 1

Step 1: Logic Making

To make a logic I used Proteus 8.10 software for designing and testing the logic using gates. You can use any other logic making software that are available online.

Select OR, AND, NOT gates and logic probe from the components library and make connections like in above figure.

For simplicity I divided the circuit into 3 parts

  1. First part with first 4 switches
  2. Second part with remaining 4 switches
  3. Third final part with s-latch

Step 2: Turning the LED ON

To turn the LED ON we have to make the following combination of the switches 10101101 starting from A to H or

  • Switch A = 1
  • Switch B = 0
  • Switch C = 1
  • Switch D = 0
  • Switch E = 1
  • Switch F = 1
  • Switch G = 0
  • Switch H = 1

Step 3: Soldering the Logic Gates IC's

Place the logic gate onto vero-board (prototyping board) and make the voltage connections first. The 16th pin of the IC is positive (+ve) pin and the 8th pin is the ground (-ve) pin.

Make all the gates connections as shown the schematic along with the switches and don't forget to use pull down resistors on the input pins of logic gates otherwise the output will not be stable.

After making all the connections the final circuit will look like this as shown in above figures.

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