New York, NY IMG HI 58° LO 56° Home About Contact
IMG-LOGO
Home Electrical and Electronics Digital Electronics Verification of the truth tables of TTL gates
Digital Electronics Lab Experiments

Verification of the truth tables of TTL gates



Aim

Verification of the truth tables of TTL gates.

Apparatus Required:

Digital lab kit, single strand wires, breadboard, TTL IC’s AND (IC-7408), OR (IC-7432), NAND (IC-7400), NOR (IC-7402), NOT (IC-7404) and NOR (IC-7486).

Theory:

Logic gates are idealized or physical devices implementing a Boolean function, which it performs a logical operation on one or more logical inputs and produce a single output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and unlimited fan out or it may refer to anon-ideal physical device.

The main hierarchy is as follows: -

  1. Basic Gates
  2. Universal Gates
  3. Advanced Gates

Basic Gates

AND Gate: The AND gate performs a logical multiplication commonly known as AND function. The output is high when both the inputs are high. The output is low level when any one of the inputs is low.

AND Gate

OR Gate: The OR gate performs a logical addition commonly known as OR function. The output is high when any one of the inputs is high. The output is low level when both the inputs are low.

OR Gate

NOT Gate: The NOT gate is called an inverter. The output is high when the input is low. The output is low when the input is high.

NOT Gate

Universal Gates

NAND Gate: The NAND gate is a contraction of AND-NOT. The output is high when both inputs are low and any one of the input is low. The output is low level when both inputs are high.

NAND Gate

NOR Gate: The NOR gate is a contraction of OR-NOT. The output is high when both inputs are low. The output is low when one or both inputs are high.

NOR Gate

Advanced Gates

X-OR Gate: The output is high when any one of the inputs is high. The output is low when both the inputs are low and both the inputs are high.

X-OR Gate

AND Gate: The output is high when any one of the inputs is high. The output is low when both the inputs are low and both the inputs are high.

NAND Gate

Procedure:

  1. Place the breadboard gently on the observation table.
  2. Fix the IC which is under observation between the half shadow line of breadboard, so there is no shortage of voltage.
  3. Connect the wire to the main voltage source (Vcc) whose other end is connected to last pin of the IC (14 place from the notch).
  4. Connect the ground of IC (7th place from the notch) to the ground terminal provided on the digital lab kit.
  5. Give the input at any one of the gate of the ICs i.e. 1st, 2nd, 3rd, 4th gate by using connecting wires. (In accordance to IC provided).
  6. Connect output pins to the led on digital lab kit.
  7. Switch on the power supply.
  8. If LED glows red then output is true, if it glows green output is false, which is numerically denoted as 1 and 0 respectively. The Color can change based on the IC manufacturer it’s just verification of the Truth Table not the color change.
  9. Result:

    Thus the logic gates are studied and their truth tables were verified.

    Precautions:-

    1. All connections should be made neat and tight.
    2. Digital lab kits and ICs should be handled with utmost care.
    3. While making connections main voltage should be kept switched off.
    4. Never touch live and naked wires.











    5. Subscribe

      Get all latest content delivered to your email a few times a month.