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Practical Uses of Logic Gates

  2. LOGIC GATES • The logic gates are the devices that performs basic logical functions that are fundamental to digital circuits. • It performs a logical operation on one or more binary inputs and produces a single binary output.
  3. TYPES OF LOGIC GATES • There are 7 types of logic gates. • Out of 7 types of logic gates, 3 are basic logic gates (AND,OR,NOT) and 4 of them are derived logic gates (NAND, NOR, X-OR, X-NOR). • Derived logic gates are the gates that are derived from the basic logic gates.
  6. HOW LOGIC GATES ARE MADE ? • Made using digital circuits and components like Transistor, Resistor and Diodes. • Specific implementation depends on the type of gate and technology used. Transistor Resistor Diode
  8. AND GATE • AND Gate performs logical AND operation. • The output of AND gate isTrue only when its all input are true. If one input is False then the output is also False. • Boolean Expression :Y = A.B where A and B are inputs andY is output • Mostly used in digital data transmission for either allowing or disallowing the data through a channel • Used in alarm circuits, automatic temperature-regulating circuits, etc.
  9. AND GATE USE IN BURGLAR ALARM Motion Sensor Alarm Switch AND GATE Burglar Alarm On/Off On/Off If the alarm switch is ‘ON’ and if a burglar enters into the room, then he/she will set the motion sensor switch “ON”, the alarm is activated.
  10. OR GATE • OR Gate performs logical OR operation. • The output of OR gate isTrue if atleast one input isTrue • Boolean Expression :Y = A + B where A and B are inputs andY is output • If occurrence of one or more than one event is to be detected and action is to be taken then OR gate can be used.
  11. OR GATE USE IN DORBELL SYSTEM Front Door Switch Back Door Switch Doorbell If either the front door switch or the back door switch is pressed, the doorbell rings. OR GATE
  12. NOT GATE • NOT Gate performs logical NOT operation. • The output of NOT gate isTrue if the input is false and vice-versa • Boolean Expression :Y = A’ where A is input andY is output • NOT gate is mostly used in temperature control systems.
  13. NOT GATE USE IN TEMPERATURE CONTROL SYSTEMS Temperature Sensor (Above 20 ℃ ) Heating System If the temperature is above 20 ℃ then the heating system turns off . If the temperature is below 20 ℃ then the heating system turns on. NOT GATE On/Off
  14. NAND GATE • NAND Gate is the combination of NOT gate and AND gate. • The output of NAND gate is False if only all input isTrue. • Boolean Expression :Y = (A.B)’ where A and B are input andY is output • NAND gate are used in Failure Detection System, Freezer warning buzzer, etc.
  15. NAND GATE USE IN FAILURE DETECTION SYSTEM Alarm While all the devices are working the input to the NAND Gate are 111 so the output is 0. But if a device stops working then the output of NAND gate will become 1 and the alarm will ring. Device 1 Device 2 Device 3
  16. NOR GATE • NOR Gate is the combination of NOT gate and OR gate. • The output of NOR gate isTrue if only all input are False else the output will be False. • Boolean Expression :Y = (A + B)’ where A and B are input andY is output • NOR gate are used mostly in Mixer Tanks in Industries.
  17. NOR GATE USE IN MIXER TANK Ingridient 2 Ingridient 1 Motor Mixer tank When the both ingridients are filled up in the tank the input will be 0 and the NOR gate will give output 1 and the motor of the mixer starts
  18. X-OR GATE (EXCLUSIVE OR) • X-OR gate is a digital logic gate that gives true output if the number of true inputs are odd else it will give false output. • Boolean Expression :Y = A’ . B + A . B’ where A and B are input andY is output • X-OR gate can be used in the conveyer belts in industries.
  19. X-OR GATE USE IN CONVEYER BELT Box Box Box Box Conveyor Belt Controller Color Sensor Motor In the conveyer belt above, when the orange boxes are detected by the color sensor then the both inputs will be 1 but when a black box arrives the color sensor input will change to 0 which makes the output of X-OR gate 1 and the motor will activate and the black box will be kicked out. Orange color is set true
  20. X-NOR GATE (EXCLUSIVE NOR) • X-NOR gate is a digital logic gate that gives output the complement of output of X-OR gate • Boolean Expression :Y = A . B + A’ . B’ where A and B are input andY is output • X-NOR gate are used mainly in Parity Checkers, Computers, Mobile Phones, and are used for error detection in data transmission systems like Anti-Lock Braking System, Engine Control Unit, Heart Monitors, ECG, etc.
  21. X-NOR GATE USE IN PARITY CHECKER CIRCUIT A B C P Cp A B C P Cp 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 1 1 1 0 1 0 0 0 0 1 0 1 1 0 1 1 0 1 0 1 1 1 0 ODD PARITY CHECKER If the 4-bit received message contains even number of 1 then the value of Parity Checker (Cp) is 1 which means error and the data is invalid and If the 4-bit message contains odd number of 1 then the value of Cp is 0 which means no error.