Category Science

Although appliances containing electronic circuits can perform very complicated tasks and even appear to think for themselves, they are operated entirely by electrical current. This cannot “think” but it can be turned on or off, increased or decreased, or caused to change direction by electronic components. The activity in any one part of a circuit depends on whether electrical current is detected or not. This can be represented by a 1 if a current is detected or a 0 if it is not. Binary code uses only the digits and 1, so it enables an electronic device to perform calculations.

A binary code represents text, computer processor instructions, or any other data using a two-symbol system. The two-symbol system used is often “0” and “1” from the binary number system. The binary code assigns a pattern of binary digits, also known as bits, to each character, instruction, etc. For example, a binary string of eight bits can represent any of 256 possible values and can, therefore, represent a wide variety of different items.

In computing and telecommunications, binary codes are used for various methods of encoding data, such as character strings, into bit strings. Those methods may use fixed-width or variable-width strings. In a fixed-width binary code, each letter, digit, or other character is represented by a bit string of the same length; that bit string, interpreted as a binary number, is usually displayed in code tables in octal, decimal or hexadecimal notation. There are many character sets and many character encodings for them.

A bit string, interpreted as a binary number, can be translated into a decimal number. For example, the lower case a, if represented by the bit string 0100001 (as it is in the standard ASCII code), can also be represented as the decimal number “97”.

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An electronic calculator has many integrated circuits inside, capable of making complicated calculations. The key pad sends signals through the circuits. The display shows the digits as they are keyed in and gives the answer when the calculation is finished. Keys marked with an M cause circuits to memorize certain numbers so that they can be reintroduced later in the calculation. As there is a key for entering the decimal point, the calculator can deal with both very small and very large numbers.

Tapping numbers into a calculator sure is easy, with your numerical query answered in seconds. However, with each sum a series of complex processes and components come into play.

Components first. A standard calculator includes a plastic casing, rubber button matrix, circuit board, single-chip CPU, battery array and liquid crystal display (LCD). More advanced models come equipped with a solar cell stack and/or integrated memory chips -the former used to charge the internal battery with the Sun’s energy, and the latter to store advanced calculations or equations.

Now let’s move on to the processes. Take a sum like ‘2 + 2’. When a user presses the 2 button on the rubber matrix, it deforms, forcing a bottom-mounted electrical contact onto the circuit board below and creating a connection. This causes electricity to flow to a pair of transistor switches on the board that convert the current into an on-off binary equivalent (a combination of is and os).

Next, when the V button is pressed, the inputted 2 is stored in its binary form by the calculator’s CPU, before resetting the input state to a receptive position. After the next 2 is inputted, the CPU sends both numbers to a logic gate as soon as the ‘=’ sign is hit.

Logic gates are electrical circuits with two inputs and only one output which execute logical operations that, in this context, are the adding, subtracting, multiplying and dividing processes. The inputs are sent in binary form to a logic gate, processed and then outputted as a single output – ie the number 4 in binary code. Finally, the answer is routed to the device’s LCD, where the digit 4’s binary is converted into segmented, illuminated lines that can be read off the display bar.

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Logic gates are combinations of resistors that make it possible for an electronic circuit to carry out calculations. Different kinds of gates affect the output of electrical current, depending on the input. Most logic gates have two input points and one output point.

A logic gate is a basic building block of a digital circuit that has two inputs and one output. The relationship between the i/p and the o/p is based on certain logic. These gates are implemented using electronic switches like transistors, diodes. But, in practice basic logic gates are built using CMOS technology, FETS and MOSFET(Metal Oxide Semiconductor FET)s. Logic gates are used in microprocessors, microcontrollers, embedded system applications and in electronic and electrical project circuits. The basic logic gates are categorized into seven: AND, OR, XOR, NAND, NOR, XNOR and NOT.

AND Gate

The AND gate is a digital logic gate with ‘n’ i/ps one o/p, which perform logical conjunction based on the combinations of its inputs. The output of this gate is true only when all the inputs are true. When one or more inputs of the AND gate’s i/ps are false, then only the output of the AND gate is false.

OR Gate

The OR gate is a digital logic gate with ‘n’ i/ps and one o/p, that performs a logical conjunction based on the combinations of its inputs. The output of the OR gate is true only when one or more inputs are true. If all the i/ps of the gate are false, then only the output of the OR gate is false.

NOT Gate

The NOT gate is a digital logic gate with one input and one output that operates an inverter operation of the input. The output of the NOT gate is the reverse of the input. When the input of the NOT gate is true then the output will be false and vice versa. The symbol and truth table of a NOT gate with one input is shown below. By using this gate, we can implement NOR and NAND gates.

NAND Gate

The NAND gate is a digital logic gate with ‘n’ i/ps and one o/p, that performs the operation of the AND gate followed by the operation of the NOT gate. NAND gate is designed by combining the AND and NOT gates. If the input of the NAND gate high, then the output of the gate will be low.

NOR Gate

The NOR gate is a digital logic gate with n inputs and one output, that performs the operation of the OR gate followed by the NOT gate. NOR gate is designed by combining the OR and NOT gate. When any one of the i/ps of the NOR gate is true, then the output of the NOR gate will be false. 

Exclusive-OR Gate

The Exclusive-OR gate is a digital logic gate with two inputs and one output. The short form of this gate is Ex-OR. It performs based on the operation of OR gate. . If any one of the inputs of this gate is high, then the output of the EX-OR gate will be high. 

Exclusive-NOR Gate

The Exclusive-NOR gate is a digital logic gate with two inputs and one output. The short form of this gate is Ex-NOR. It performs based on the operation of NOR gate. When both the inputs of this gate are high, then the output of the EX-NOR gate will be high. But, if any one of the inputs is high (but not both), then the output will be low.

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Silicon chips are too small to be connected by ordinary wire, however fine it is. Instead, minute “tracks” of a conducting material such as copper are printed on the circuit board to link the silicon chips.

Open up a television or a radio and you’ll see it’s built around a printed circuit board (PCB): a bit like an electric street-map with small electronic components (such as resistors and capacitors) in place of the buildings and printed copper connections linking them together like miniature metal streets. Circuit boards are fine in small appliances like this, but if you try to use the same technique to build a complex electronic machine, such as a computer, you quickly hit a snag. Even the simplest computer needs eight electronic switches to store a single byte (character) of information. So if you want to build a computer with just enough memory to store this paragraph, you’re looking at about 750 characters times 8 or about 6000 switches—for a single paragraph! If you plump for switches like they had in the ENIAC—vacuum tubes about the size of an adult thumb—you soon end up with a whopping great big, power-hungry machine that needs its own mini electricity plant to keep it running.

Integrated circuits changed all that. The basic idea was to take a complete circuit, with all its many components and the connections between them, and recreate the whole thing in microscopically tiny form on the surface of a piece of silicon. It was an amazingly clever idea and it’s made possible all kinds of “microelectronic” gadgets we now take for granted, from digital watches and pocket calculators to Moon-landing rockets and missiles with built-in satellite navigation.

Integrated circuits fit into printed circuit boards (PCBs) like the green one you can see here. Notice the thin tracks linking the “legs” (terminals) of two different ICs together. Other tracks link the ICs to conventional electronic components such as resistors and capacitors. You can think of the tracks as “streets” making paths between “buildings” where useful things are done (the components themselves). There’s also a miniaturized version of a circuit board inside an integrated circuit: the tracks are created in microscopic form on the surface of a silicon wafer.

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A silicon chip is also known as an integrated circuit. It is a complete circuit, perhaps containing thousands of electronic components, that is printed on a thin wafer of an element called silicon. The chip is protected by a covering called a capsule, which is the part we normally see. Little metal feet allow the chip to be connected to other chips and components.

A Silicon chip is an integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or “chip”) of semiconductor material, normally silicon. The IC’s size, cost, mass production capability, reliability and building-block approach to circuit design ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world. IC’s are called “silicon” chips not because they’re silicon but because the semi-conductors (transistors) are planted in silicon (it’s just the way manufacturers fabricates them to make them so small).

Silicon in the pure form is a semiconductor, which means it possess properties of both a metal (which conducts electricity) and an insulator (which blocks electricity), by controlling semiconducting silicon, manipulation of electrical signals can be done at room temperature that ultimately are the building blocks of electronic circuits. Silicon is actually not the most optimal electronic material, has an indirect band gap which is less efficient than materials with direct band gaps. But it dominates other materials with better electronic properties because it is cheap and extremely abundant. One reason for choosing silicon over other material is that it operates better at high temperatures because the bonds with the electrons are stronger. Another reason silicon became dominant because it is very easy to create a high quality thin insulator on the surface of a silicon chip, as silicon can be put in a hot furnace with oxygen and it will form a thin film of silicon dioxide which performs as an excellent insulator which gave it a huge advantage when MOSFETs were first created. This insulator is used to reduce power consumption and increase performance.

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Electronic components affect the way that current flows around a circuit. There are numerous basic electronic components that are used for building electronic circuits. Without these components, circuit designs are never complete or didn’t function well. These components include resistors, diodes, capacitors, integrated circuits, and so on. Some of these components consist of two or more terminals which are soldered to circuit boards. Some may be packaged type like integrated circuits in which different semiconductor devices are integrated. Here is a brief overview on each of these basic electronic components and you can get in depth information by clicking links attached to each component.

An electronic circuit comprises of various types of components, which are classified into two types: active components like transistors, diodes, IC’s; and passive components like capacitors, resistors, inductors, etc.

Resistors

A resistor is a two-terminal passive electronic component, used to oppose or limit the current. Resistor works based on the principle of Ohm’s law which states that “voltage applied across the terminals of a resistor is directly proportional to the current flowing through it” Resistors are further classified based on the following specifications such as the power rating, type of material used and resistance value. This resistor types are used for different applications.

Fixed resistors:

This type of resistor is used to set the right conditions in an electronic circuit. The values of resistance in fixed resistors are determined during the design phase of the circuit, based on this there is no need to adjust the circuit.

Variable resistors:

A device that is used to change the resistance according to our requirements in an electronic circuit is known as a variable resistor. These resistors comprise of a fixed resistor element and a slider which taps on to the resistor element. Variable resistors are commonly used as a three terminal device for calibration of the device.

Capacitors:

A capacitor made from two conductive plates with an insulator between them and it stores electrical energy in the form of an electric field. A capacitor blocks the DC signals and allows the AC signals and also used with a resistor in a timing circuit. These capacitors are different types like film, ceramic, electrolytic and variable capacitors. For finding its value number and color coding methods are used and it also possible to find the capacitance value with LCR meters.

Active Electronic Components

These components rely on a source of energy and are able to control the electron flow through them. Some of these components are semiconductors like diodes, transistors, integrated circuits, various displays like LCD, LED, CRTs and power sources like batteries, PV cells and other AC and DC supply sources.

Diodes

A diode is a device that allows current to flow in one direction and usually made with semiconductor material. It has two terminals, anode and cathode terminals. These are mostly used in converting circuits like AC to DC circuits. These are are of different types like PN diodes, Zener diodes, LEDs, photo diodes, etc.

Transistors

A transistor is a three terminal semiconductor device. Mostly it is used as switching device and also as an amplifier. This switching device can be a voltage or current controlled. By controlling the voltage applied to the one terminal controls the current flow through the other two terminals. Transistors are of two types, namely bipolar junction transistor (BJT) and field effect transistors (FET). And further these can be PNP and NPN transistors.