Procedure
In the previous experiment, a NOT gate was demonstrated. A NOT gate has just one input. In case of gates with multiple inputs, the situation might get a little trickier. So to demonstrate that idea, we are going to use a 2 input logic gate in this experiment. Except NOT gate, all other gates have at least 2 input pins. This time, demonstration will be carried out with a AND gate. Just like before, the schematic has three parts with the same differences shown for the NOT gate experiment.
Components:
1. One CD4081 IC (AND gate)
2. One 2.2KΩ Resistor, Two 10KΩ Resistor
3. One LED (any color)
4. Two tap switch
Steps:
1. Set up the circuit (ii) using schematic above. The schematic shows a single gate. From the schematic, it is seen that the input of the AND gate is at Pin 1 and Pin 2 and output is at Pin 3. So, the LED is connected to pin 3 via the resistor and the input signal goes to the Pin 1 & Pin 2 via the 10KΩ resistor.
2. Connect the Terminus power to the breadboard power rails.
3. Initially both input are connected to GND i.e. the input is digital LOW. Observe the LED. The LED should be turned OFF.
4. Next, push one of the tap switches to feed one of the input with digital HIGH and observe the LED. The LED should be turned OFF.
5. Finally, feed both input a digital HIGH by pushing both tap switches and observe the LED. The LED should be turned ON.
And again, take a look at the truth table of the AND gate. See the schematic as well. From the steps, you can see that at the beginning, both inputs of the AND gate are LOW. From the truth table, you can see that for this combination of inputs, the output should be LOW. That is exactly what we are getting (see the LED is turned OFF).
Next, one input is connected to ground rail to feed the input digital LOW and another to positive rail to make the input HIGH. This combination gives output of LOW (LED is off).
And finally, we connected both inputs to ground rail to set both inputs to HIGH. This gives us output of HIGH. That is what we are getting as the LED is glowing.
