How to Create a NOR Gate Using a NAND Gate

A digital NAND (Negated AND) gate performs the opposite function to a digital AND gate, in that it will only output a LOW signal if both inputs are HIGH. Like NOR gates, NAND gates are universal, which means that a number of them combined can be used to replicate the function of any other type of logic gate. By connecting four NAND gates together, a working NOR gate can be created.

Things You'll Need

• 74HC00 Quad 2 Input NAND gate Integrated Circuit
• Breadboard
• 5 Volt power supply
• Jumper wires
• Digital multimeter

Instructions

Make the Connections

1. Place the 74HC00 quad two input NAND gate IC on the breadboard. This integrated circuit (IC) has four NAND gates built into the same chip. Note the orientation, the top of the IC has a notch cut out, with pin 1 to the left of the notch and pin 14 to the right of the notch. Other quad two input NAND gates can be used, as long as the correct power supply voltage is used for the particular IC.

2. Connect the ground (0 volt) from the power supply to pin 7 of the 74HC00. The pin out for the 74HC00 can be found in its data sheet. Connect the positive (5 volt) output from the power supply to pin 14 of the 74HC00. These connections provide power and ground to the IC.

3. Connect up the first NAND gate. This should have one input connected to 5V (digital HIGH) and the other will be used for the input signal "INPUT A." Connect pin 1 of the 74HC00 IC to the 5 volt output from the power supply. Connect a wire to pin 2, which will be used as "INPUT A."

4. Connect the second NAND gate, which again has one input connected to 5V and the other used as an input. Connect pin 4 of the 74HC00 IC to the 5 volt output from the power supply and connect a wire to pin 5 to be used as "INPUT B."

5. Connect the outputs from the first and second NAND gates to the inputs of the third NAND gate. To do this, connect pin 3 of the 74HC00 IC to pin 9 and pin 6 of the IC to pin 10.

6. Connect one input to 5V on the fourth NAND gate and the other input to the output of the third NAND gate. Connect pin 12 of the 74HC00 to the 5 volt output from the power supply. Connect pin 8, which is the output of the third NAND gate, to pin 13, which is the second input for the fourth NAND gate.

7. Connect a wire to the output of the fourth NAND gate, which will be the final output. The wire connects to pin 11 of the 74HC00 IC.

Test the Circuit

1. Turn on the power supply to the 74HC00 IC.

2. Connect both INPUT A (pin 2) and INPUT B (pin 5) to the ground on the power supply. This makes both inputs digital LOW. Measure between pin 11, which is the output of the NOR gate, and ground using the digital multimeter set to its voltage measurement mode. This should measure 5 volts (digital HIGH).

3. Connect one or both of the inputs to the 5 volt output on the power supply (digital HIGH). Measure the output between pin 11 and ground with the digital multimeter, which will measure 0 volts (digital LOW).

4. Study the truth table below and try the different combinations of inputs to verify the NOR gate is working correctly:

   A B OUTPUT

   0 0 1

   1 0 0

   0 1 0

   1 1 0

Tips & Warnings

• Do not provide power to any of the NAND gate inputs unless the Vcc pin (pin 14) has power and the ground (pin 7) is connected. Doing so could result in damage to the integrated circuit.

References

• All About Circuits: Gate Universality : Logic Gates

Resources

• Datasheet Catalog: Philips 74HC00 Datasheet