When I was in college I don't understand what a logic circuit is, I just thought it's useless, I don't know it has a real life applications. It wasn't my fault, it's my teacher fault. He didn't explain it in a real life form, he just kepts explaining that logic circuits is use by computers to manipulate and process data, but now I understand the indept of logic circuit, it's applications and how it works.
This tutorial will be taking us through the world if logic, what it is, it's applications and how it works.
What is a logic circuit?
Logic circuit are the basis of modern computers and electronic devices. Digital devices process information in form of 0 and 1 with the use of logic circuit. In engineering, 1 means fully ON, 0 means fully OFF. (1) indicates that electric current flows through a circuit at the voltage from it power source, while (0) means that there is no current flowing through a circuit from a power source.
Actually, transistors which are three legged semiconductor devices are used in logic circuits for switching ON and OFF electric current/ signals for it to be processed.
So, simply logic circuits are electronics circuits which are made up of logic gates which are used for performing logic reasoning, controls and calculations. Logic gates are either transistors like BJTs or FETs, or either BJTs and FETs combined together as an integrated circuit (IC), which receives input signals in form of 0&1(ON and OFF) and then process it and output it as a processed digital signal.
The components of the gates pass or block a clock pulse as it travels through them, and the output bits of the gates control other gates or output the result. There are three basic kinds of logic gates, called “and,” “or,” and “not.” By connecting logic gates together, a device can be constructed that can perform basic arithmetic functions.
Basically, gates are switching electronic components which are transistors or integrated circuits. They are usually represented as drawings, this switching components can either have either AND, OR or NOT characteristics.
Basic logic gates.
1. AND gate.
The AND gate is a characteristics of a digital switching electronic component that allows two or more input signals to be executed at once and then give out an output signal. That is, the output signal of an AND gate depends on the input signals which can be 0 or 1( ON or OFF).
Symbolic Representation of AND gate.
For an AND gate, if one or all of the input signals is OFF(0) then the output will be 0 (OFF). The output will only be 1(ON) when all the input signals are 1(OFF).
Simply, in computer and electronics engineering for an AND gate if of the input signal voltage is low (0v) the output signal voltage will be OFF (0v), this means that the gate (transistor) won't allow the current to pass through it, therefore blocking current flow. In electric circuits a typical AND gate is a BJT NPN or PNP transistor.
New to transistors? click 👉 here to learn more about it.
2. OR gate.
This type of gate or switching component gives an output signal of 1(ON) only when one or more of the input signals is 1(ON). That means of the input signals are all 0(OFF) then, the output is 0(OFF).
No matter what the inputs are, as long as it has one or more signals which is/are 1(ON) as input the output will also be 1 (ON.)
3. NOT gate.
This type of gate is somehow different from other gates. It's also known as an inverter. It only input a signal and output a signal, i.e one input and one output.
The output is always the inverse of the input.
Symbolic representation of NOT gate.
If the input signal of a NOT gate is 1 (ON) then the output signal will be 0.(OFF).
If u take a close look at the circuit below, the switch is not connecting to the ground which means an input signal of 0v is applied to the gate, but the LED switched on.
Working principle of logic gates.
To understand the working principle of Logic Gates, let us consider the example of Street Lighting System. Fig below shows the Circuit Diagram of Street Lighting System which mainly consists of Logic Gate (s) (NOT and OR Gate), Switch and Light Sensor. The operational condition for the street light to function is as follows:
Switch: On = 1,Off = 0
Light Sensor: Dark = 0, Bright = 1
Street Light: On = 1, Off = 0.
Applications of logic circuits.
Logic gates are used in microcontrollers, microprocessors, electronic and electrical project circuits, and embedded system applications.
NAND Gates are used in Burglar alarms and buzzers.
They are basically used in circuits involving computation and processing.
They are also used in push button switches. E.g. Door Bell.
They are used in the functioning of street lights.
AND Gates are used to enable/inhibit the data transfer function.
They are also used in TTL (Transistor Transistor Logic) and CMOS circuitry.
In other words, microprocessors, microchips and Integrated circuits are made up of logic gates (different types of transistors) which are combined together to process data, control and execute commands
When I was in secondary school I don't understand what a logic circuit is, I just thought it's useless, I don't know it has a real life applications. It wasn't my fault, it's my teacher fault. He didn't explain it in a real life form, he just kepts explaining that logic circuits is use by computers to manipulate and process data, but now I understand the indept of logic circuit, it's applications and how it works.
This tutorial will be taking us through the world if logic, what it is, it's applications and how it works.
What is a logic circuit?
Logic circuit are the basis of modern computers and electronic devices. Digital devices process information in form of 0 and 1 with the use of logic circuit. In engineering, 1 means fully ON, 0 means fully OFF. (1) indicates that electric current flows through a circuit at the voltage from it power source, while (0) means that there is no current flowing through a circuit from a power source.
Actually, transistors which are three legged semiconductor devices are used in logic circuits for switching ON and OFF electric current/ signals for it to be processed.
So, simply logic circuits are electronics circuits which are made up of logic gates which are used for performing logic reasoning, controls and calculations. Logic gates are either transistors like BJTs or FETs, or either BJTs and FETs combined together as an integrated circuit (IC), which receives input signals in form of 0&1(ON and OFF) and then process it and output it as a processed digital signal.
The components of the gates pass or block a clock pulse as it travels through them, and the output bits of the gates control other gates or output the result. There are three basic kinds of logic gates, called “and,” “or,” and “not.” By connecting logic gates together, a device can be constructed that can perform basic arithmetic functions.
Basically, gates are switching electronic components which are transistors or integrated circuits. They are usually represented as drawings, this switching components can either have either AND, OR or NOT characteristics.
Basic logic gates.
1. AND gate.
The AND gate is a characteristics of a digital switching electronic component that allows two or more input signals to be executed at once and then give out an output signal. That is, the output signal of an AND gate depends on the input signals which can be 0 or 1( ON or OFF).
Symbolic Representation of AND gate.
For an AND gate, if one or all of the input signals is OFF(0) then the output will be 0 (OFF). The output will only be 1(ON) when all the input signals are 1(OFF).
Simply, in computer and electronics engineering for an AND gate if of the input signal voltage is low (0v) the output signal voltage will be OFF (0v), this means that the gate (transistor) won't allow the current to pass through it, therefore blocking current flow. In electric circuits a typical AND gate is a BJT NPN or PNP transistor.
New to transistors? click 👉 here to learn more about it.
2. OR gate.
This type of gate or switching component gives an output signal of 1(ON) only when one or more of the input signals is 1(ON). That means of the input signals are all 0(OFF) then, the output is 0(OFF).
No matter what the inputs are, as long as it has one or more signals which is/are 1(ON) as input the output will also be 1 (ON.)
3. NOT gate.
This type of gate is somehow different from other gates. It's also known as an inverter. It only input a signal and output a signal, i.e one input and one output.
The output is always the inverse of the input.
Symbolic representation of NOT gate.
If the input signal of a NOT gate is 1 (ON) then the output signal will be 0.(OFF).
If u take a close look at the circuit below, the switch is not connecting to the ground which means an input signal of 0v is applied to the gate, but the LED switched on.
Working principle of logic gates.
To understand the working principle of Logic Gates, let us consider the example of Street Lighting System. Fig below shows the Circuit Diagram of Street Lighting System which mainly consists of Logic Gate (s) (NOT and OR Gate), Switch and Light Sensor. The operational condition for the street light to function is as follows:
Switch: On = 1,Off = 0
Light Sensor: Dark = 0, Bright = 1
Street Light: On = 1, Off = 0.
Applications of logic circuits.
Logic gates are used in microcontrollers, microprocessors, electronic and electrical project circuits, and embedded system applications.
NAND Gates are used in Burglar alarms and buzzers.
They are basically used in circuits involving computation and processing.
They are also used in push button switches. E.g. Door Bell.
They are used in the functioning of street lights.
AND Gates are used to enable/inhibit the data transfer function.
They are also used in TTL (Transistor Transistor Logic) and CMOS circuitry.
In other words, microprocessors, microchips and Integrated circuits are made up of logic gates (different types of transistors) which are combined together to process data, control and execute commands
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Logic circuits