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Machine Learning

posted 15 hours 6 minutes ago


Allo, Google’s AI-enhanced answer to ‘smart messaging’ on mobile, is here. Designed to keep users from straying outside the app to search for things on the internet, Allo is the first Google product to feature its AI “assistant.”
Suggestions from the assistant are meant to be conversational, and can be plugged into existing conversations or had between you and Google alone. Google is expected the start rolling out the assistant to other products this fall, starting with Google Home, as part of the company’s ongoing push toward AI. Allo comes on the heels of Duo, Google’s video calling app, which has been downloaded 10 million times since it was released last month. Taken together, the two represent Google’s attempt to grab some of the direct messaging market while integrating machine learning across its suite of consumer-oriented products. “We don’t see messaging as a solved problem,” said Nick Fox, Google’s vice president of communications products. Fox said Allo is about “getting things done right in your chat. We think the enabler here is AI.”
Fox stressed that the goal of Allo is to keep the automated suggestions simple and subtle, so as not to replace other apps or search generally, but rather to supplement them. Like Duo, Allo uses your cell phone number, so there’s no need to create a separate user account. Allo does associate with your existing Google account, however, giving it access to a host of personal information, such as images you’ve saved with Google’s cloud photo storage. The more you use the assistant, the more it learns about you. Once you tell Allo your favorite sports team, for example, you can recall news about the team without using its name. “Google has been a one on one experience for 18 years,” Fox said, adding that with Allo, “now it’s like multiplayer.”
When you turn Allo on, it asks for your location. This gives it the ability to search for things you might be likely to ask it for, such as the weather or nearby restaurants. Allo retains the context of a conversation when you query it , mimicking an actual conversation you’d have with a friend. Let’s say you invite someone to dinner via Allo, and your friend asks the assistant to find nearby restaurants. Both users would see the same results, and if one person wanted to see just the restaurants that are open or those with the highest rating, for example, the assistant would filter down results accordingly, all within the app itself.
The assistant gives two types of results. The first is what you’ve come to expect from any search engine, and includes basic information on the subject you’ve asked about. Beneath that is a row of suggested information based on what you asked, when you asked and what you’ve asked in the past. Throughout the app, results are doled out in “bite size snacks,” Fox said. Think of results less like a comprehensive Wikipedia page, and more direct responses to the question you’ve just asked. In addition to quickly surfacing web results, Allo lets you respond to messages with pre-determined phrases that are common replies to questions or prompts. So if your friend sends you a selfie, for example, an automated reply might be “What a great smile.”
The risk of any smart messaging system, Fox said, is that it gets in the way of the conversation. Google’s goal is to have its assistant be as unobtrusive as possible, while still adding an element of ease and simplicity that people have come to expect. “The user is in control,” he said. “That’s a theme throughout.”
Among the other features of Allo: Photos sent through the app fill up more than half your screen, and appear edge to edge width on your phone rather than in their own message bubble that needs to be opened. Allo’s “whisper” or “shout” functions allow you to control the size of text or emojis. In addition to all the standard emojis you’re familiar with, you can download a slew of “sticker packs,” featuring cartoon-like images created by artists Google has contracted with. Allo’s “incognito” mode features end-to-end encryption, and allows you or the person you are messaging with to set messages to expire. When set to incognito, Allo defaults to discreet notifications that don’t include the sender’s identity or content of the message until the app has been opened on your phone.
For now, the assistant won’t share personal information–such as photos you’ve stored in the cloud–with contacts you are messaging, though this will likely happen later as Google tweaks with limits on the type of information that’s shared. The assistant, which Google says it will begin rolling out in other products this fall, is in “preview” edition, and will prompt you for feedback on individual chats. If the person you are messaging doesn’t have the app installed, the message is still delivered via standard SMS text. The sender will get a notification saying the recipient doesn’t have Allo, and the recipient will see a link to download the app. Allo is available for both Android and iOS.
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Computer Science

posted 5 days 19 hours ago

Software architecture serves as the blueprint for both the system and the project developing it, defining the work assignments that must be carried out by design and implementation teams.

The architecture is the primary carrier of system qualities such as performance, modifiability, and security, none of which can be achieved without a unifying architectural vision.

Architecture is an artifact for early analysis to make sure that a design approach will yield an acceptable system. By building effective architecture, you can identify design risks and mitigate them early in the development process.

The Goals of Architecture

  1. Expose the structure of the system but hide the implementation details.
  2. Realize all of the use cases and scenarios.
  3. Try to address the requirements of various stakeholders.
  4. Handle both functional and quality requirements.


The Principles of Architecture Design

  • What are the foundational parts of the architecture that represent the greatest risk if you get them wrong?
  • What are the parts of the architecture that are most likely to change, or whose design you can delay until later with little impact?
  • What are your key assumptions, and how will you test them?
  • What conditions may require you to refactor the design?

Key Architecture Principle

  • Build to change instead of building to last. Consider how the application may need to change over time to address new requirements and challenges, and build in the flexibility to support this.
  • Model to analyze and reduce risk. Use design tools, modeling systems such as Unified Modeling Language (UML), and visualizations where appropriate to help you capture requirements and architectural and design decisions, and to analyze their impact. However, do not formalize the model to the extent that it suppresses the capability to iterate and adapt the design easily.
  • Use models and visualizations as a communication and collaboration tool. Efficient communication of the design, the decisions you make, and ongoing changes to the design, is critical to good architecture. Use models, views, and other visualizations of the architecture to communicate and share your design efficiently with all the stakeholders, and to enable rapid communication of changes to the design.
  • Identify key engineering decisions. Use the information in this guide to understand the key engineering decisions and the areas where mistakes are most often made. Invest in getting these key decisions right the first time so that the design is more flexible and less likely to be broken by changes.


When testing your architecture, consider the following questions:

  • What assumptions have I made in this architecture?
  • What explicit or implied requirements is this architecture meeting?
  • What are the key risks with this architectural approach?
  • What countermeasures are in place to mitigate key risks?
  • In what ways is this architecture an improvement over the baseline or the last candidate architecture?

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Computer Science

posted 6 days 10 hours ago


Bubble sort is a simple sorting algorithm. This sorting algorithm is comparison based algorithm in which each pair of adjacent elements is compared and elements are swapped if they are not in order. This algorithm is not suitable for large data sets as its average and worst case complexity are of O(n2) where n are no. of items.


How bubble sort works?

We take an unsorted array for our example. Bubble sort take Ο(n2) time so we're keeping short and precise.



Bubble sort starts with very first two elements, comparing them to check which one is greater.



In this case, value 33 is greater than 14, so it is already in sorted locations. Next, we compare 33 with 27.


We find that 27 is smaller than 33 and these two values must be swapped.



The new array should look like this −



Next we compare 33 and 35. We find that both are in already sorted positions.



Then we move to next two values, 35 and 10.



We know than 10 is smaller 35. Hence they are not sorted.



We swap these values. We find that we reach at the end of the array. After one iteration the array should look like this −



To be precise, we are now showing that how array should look like after each iteration. After second iteration, it should look like this −



Notice that after each iteration, at least one value moves at the end.



And when there's no swap required, bubble sorts learns that array is completely sorted.



Now we should look into some practical aspects of bubble sort.



We assume list is an array of n elements. We further assume that swap function,

swaps the values of given array elements.




We observe in algorithm that Bubble Sort compares each pair of array element unless the whole array is completely sorted ascending. This may cause few complexity issues like what if the array needs no more swapping as all the elements are already ascending.

To ease-out the issue, we use one flag variable swapped which will help us to see if any swap is happened or not. If no swap is occurred, i.e. the array requires no more processing to be sorted, it will come out of the loop.

Pseudocode of BubbleSort algorithm can be written as given below −




One more issue we did not address in our original algorithm and its improvised pseudocode, that is, after every iteration the highest values settles down at the end of the array. So next iteration needs not to include already sorted elements. For this purpose, in our implementation, we restrict the inner loop to avoid already sorted values.



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Computer Science

posted 6 days 14 hours ago


The Internet is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide. It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. 
The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, newsgroups, voice over IP telephony, and peer-to-peer networks for file sharing.
The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, fault-tolerant communication via computer networks.The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. The funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, led to worldwide participation in the development of new networking technologies, and the merger of many networks.The linking of commercial networks and enterprises by the early 1990s marks the beginning of the transition to the modern Internet and generated a sustained exponential growth as generations of institutional, personal, and mobile computers were connected to the network. Although the Internet was widely used by academia since the 1980s, the commercialization incorporated its services and technologies into virtually every aspect of modern life.
Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world.In the 20 years since 1995, Internet use has grown 100-times, measured for the period of one year, to over one third of the world population.
Most traditional communications media, including telephony, radio, television, paper mail and newspapers are being reshaped or redefined by the Internet, giving birth to new services such as email, Internet telephony, Internet television music, digital newspapers, and video streaming websites. Newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators (e.g., Google News). 
The entertainment industry was initially the fastest growing segment on the Internet.[citation needed] The Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Online shopping has grown exponentially both for major retailers and small businesses and entrepreneurs, as it enables firms to extend their "bricks and mortar" presence to serve a larger market or even sell goods and services entirely online. Business-to-business and financial services on the Internet affect supply chains across entire industries.
The Internet has no centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own policies.Only the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise.
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Computer Science

posted 6 days 18 hours ago

Binary search is a fast search algorithm with run-time complexity of Ο(log n).

This search algorithm works on the principle of divide and conquer.

For this algorithm to work properly the data collection should be in sorted form.

Binary search is a particular item by comparing the middle most item of the collection. If match occurs then index of item is returned. If middle item is greater than item then item is searched in sub-array to the right of the middle item otherwise item is search in sub-array to the left of the middle item. This process continues on sub-array as well until the size of sub array reduces to zero.

How binary search works?

For a binary search to work, it is mandatory for the target array to be sorted. We shall learn the process of binary search with an pictorial example. The below given is our sorted array and assume that we need to search location of value 31 using binary search.


First, we shall determine the half of the array by using this formula −

Here it is, 0 + (9 - 0 ) / 2 = 4 (integer value of 4.5). So 4 is the mid of array.

Now we compare the value stored at location 4, with the value being searched i.e. 31. We find that value at location 4 is 27, which is not a match. Because value is greater than 27 and we have a sorted array so we also know that target value must be in upper portion of the array.


We change our low to mid + 1 and find the new mid value again.

Our new mid is 7 now. We compare the value stored at location 7 with our target value 31.

The value stored at location 7 is not a match, rather it is less that what we are looking for. So the value must be in lower part from this location.



So we calculate the mid again. This time it is 5.


We compare the value stored ad location 5 with our target value. We find that it is a match.


We conclude that the target value 31 is stored at location 5. Binary search halves the searchable items and thus reduces the count of comparisons to be made to very less numbers.


The pseudocode of binary search algorithm should look like this −

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posted 6 days 21 hours ago
combination of two or more antenna to givr a better directivity in a desired direction are called array antenna they are broadly classified in four category 1.broadside array 2.endfire array 3.collinear(vertical and horizontal) 4.parastic antenna(yadi uda antenna) yagi antenna is also kwon as super directivity antenna as it is having more directivity than other antenna per unit area yagi antenna is named after its founder . defination for yagi antenna is simple dipole or corrugated dipole antenna having one driven element serving as a feed to other parastic elements(reflector and director). basic properties of yagi antenna is 1.it is called beam antenna if it contain array pf three elements(director, driven element,reflector) 2.it has an unidirectional beam with a moderate directivity,low weight, low in cost and simplicty in feed design. 3. we can obtain a bandwith of 2 percent by adjustin the distance 0.25 to 0.5 lambda. 4. it has a gain of 8 db or front to back ratio of 20 db. 5. it is also called super gain antenna as it has more gain from other antenna per unit area(super directivity) 6.more elements are used for more gain but upto a certain limit after which it starts giving narrow beamwidth yagi antenna are used in televisions How to find length of director,driven element and reflector if the operating frequency is given ,then calculate lambda driven element would have a length of lambda by two director length would be 5 percent less.. that is 95 percent of lambda by two reflector length would be 5 percent more than that of 105 percent more than driven element if the frequency is given in mhz and the length of reflector,driven elemnts and director is to be found then use the formula reflector length 500/f(mhz) driven element if 475/f (mhz) director element 455/f(mhz) directivity of endfire antenna is given by D= 4n(d/lambda) where small d represent spacing between two elements gain in general is given by 4.5 A/(lambda square) where a represents the area.
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Computer Science

posted 1 week 16 hours ago

Linked List is a term very much well know among the Data Structure students.

Lets start with some fundamental concepts of Linked List.

What is Linked List?

Linked List is a sequence of data structures which are connected together via links.


What are the components of Linked List?

  1.  Link
  2. Next
  3. LinkedList

Link: Link stores data that is called element.

Next: Link stores a link to the next link that is called Next

LinkedList: A LinkedList contains the connection link to the first link called First.



Representation of Linked List


We can draw a Linked list like chain of nodes. Each node points to the next node.




Types of Linked List

  1. Simple Linked List
  2. Doubly Linked List
  3. Circular Linked List


Simple Linked List

Item navigation is forward only

Doubly Linked List

Items can be navigated forward and backward way

Circular Linked List

Last item contains link of the first element as next and first has link to last element as prev.

Basic Operations

  1. Insertion : add an operation supported by a list
  2. Deletion : Delete an element at the begining of the list
  3. Display: displaying complete list
  4. Search: search an element using given key
  5. Delete: delete an element using given key. 

Insertion Operation

Adding a new node in linked list is a more than one step activity. We shall learn this with diagrams here. First , create a node using the same structure and find the location where it has to be inserted.




Imagine that we are inserting a node B (NewNode), between A (LeftNode) and C (RightNode). Then point B.next to C

NewNode.next −> RightNode;

It should look like this −


Now the next of the node at left should point to the new node.

LeftNode.next −> NewNode;



This will put the new node in the middle of the two. The new list should look like this −


Similar steps should be taken if the node being inserted at the beginning of the list. While putting it at the end, then the second last node of list should point to new node and the new node will point to NULL.


Deletion Operation

Deletion is also a more than one step process. We shall learn with pictorial representation. First, locate the target node to be removed, by using searching algorithms.




The left (previous) node of the target node now should point to the next node of the target node −

LeftNode.next −> TargetNode.next;


This will remove the link that was pointing to target node. Now we shall remove to what target node is pointing.

TargetNode.next −> NULL;



We need to use the deleted node we can keep that in memory otherwise we can simply deallocate memory and wipe off the target node completely.



Reverse Operation

This operation is a thorough one. We need to make the last node be pointed by the head node and reverse the whole linked list.



First, we traverse to the end of the list. It should be pointing to NULL. Now we shall make it to point to its previous node −



We have to make sure that last node is not the lost node, so we'll have some temp node, which looks like the head node pointing to the last node. Now we shall make our all our left side nodes to point to their previous nodes one by one.



Except the node (first node) pointed by the head node, should point to their predecessor and making them their new successor. The first node will point to NULL. 


We'll make the head node to point the new first node by using temp node.


The linked-list is now reversed. To see linked-list implementation in C programming language.

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Electronic Engineering

posted 1 week 1 day ago
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Electronic Engineering

posted 1 week 1 day ago

Electronics has changed completely the working style of Automobiles. There are many technolgoies has been developed to enhance the automobile industires.

Lets take examples:

  • Electronic Fuel Injection(EFI)
  • Global Positioning System(GPS)
  • Computer Diagnostics
  • All-Wheel Drive / AWD

Electronic Fuel Injection(EFI)

The EFI replaced the normal carburetor.

Working of Normal Carburetor

Carburetor is a part of engine which evaporates fuels and this evaporated fuel mixes with the air and create combustion.  This created combustion provides energy to run the engine. There is a floating device in the carburetor, which regulate the amount of fuel required by the engine.

 Working of EFI

 THE EFI working style is very much different from the normal carburetor. EFI not uses that floating device to regulate the fuel supply to the engine. EFI uses meters to supply only that much of fuel required by the engine. It minimized the wastages of fuel very much. It increases the mileage of cars.

Computer Diagnostics

This technology is used to diagnose the engine of the car. It gives a alert indication to the owner of the car before real damage occurs.

It minimizes lots of accidents and unwanted breakdown of the cars.


It is another innovation in the car technology. It has given an extra power to the engines. Earlier engines were use to supply power to the two wheels of the car. But this technology is giving power to all the four wheels of the car. Due to which car speed increased extensively. The most essential power given by this technology is that now cars are very easily traveled through the hills and difficult mountains road.


Now the speed of cars increased extensively. And chances of accidents also increased. Every technology has two aspects Good and Bad. On the one hand it increases the speed and on the other hand chances of life loss and accidents increased. But our technology doesn’t stop here. It has also given Airbag technology which decreases the accidents in large scale. This airbag works on electronic sensing system. This electronic sensing system works on the measurement of quick through accelerometer.

Global Positioning System(GPS)

GPS is used in many ways. It is used for searching of stolen car. It gives a shortest route suggestion to the driver to his/her destination. GPS assistance help us through voice navigation system. It also alerts us that we have chosen wrong route to the respective destination.

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Electronic Engineering

posted 1 week 2 days ago

A radar imaging system can be thought of as an echo measurement system. The radar antenna emits thousands of pulses of microwave radiation and measures the characteristics of associated echoes.

The radar determines the range between the antenna and the reflecting object, the amplitude of the return wave, and its phase. That is, the radar can determine if the wave returns at its peak or trough, or somewhere in between.

These measurements of range, amplitude, and phase are processed together to form images and many other useful products.

The ability to penetrate clouds is the core advantage of radar imaging. Radars emit pulses of microwave energy, which have long wavelengths in comparison to sunlight, and are unaffected by cloud-cover, dust, and gas in the atmosphere. Radar is the only remote sensing technology that can almost guarantee collection regardless of weather.


  • Sunlight Not Needed: Radar does not need sunlight for illumination; it can be configured to collect images at any time of the day or night.
  • Flexible Collection: Radars can be designed with flexible collection capabilities. A single system can support high-resolution imaging over small areas, medium-resolution over medium areas, or low-resolution over large areas.
  • Multiple Microwave Bands: Radar imaging supports collection in different wavelength bands. Many systems employ X-band radiation with pulse wavelengths of roughly three centimeters, but other wavelengths are possible. For example, P-band radar has a wavelength of about one meter, which is so long that the energy penetrates vegetation and can be used to image through foliage.
  • Controlled Polarization: Radars control the orientation, or polarization, in space of the emitted waves. They are designed to image in specific polarizations, or even in multiple polarizations during the same imaging operation. Images of different polarizations record different reflectance patterns, which may reveal surface structure content, such as crop types or drainage patterns.
  • Coherent Illumination: In contrast to the random illumination of sunlight, radar energy is emitted in a controlled manner in which the wave and frequency patterns are consistent. This natural coherence means the radar data can be used to generate special products such as 3D global elevation grids and models of very slight changes in ground-surface structure over time.
  • High Resolution: The technique called Synthetic Aperture Radar (SAR) permits high-resolution imaging from any distance.

In the early days of radar imaging, the challenge was to achieve useful resolutions in the range and cross-range dimensions of the image. Good range resolution relies principally upon the properties of the transmitted waveform. But the early imaging radars, so-called real-aperture radars, had cross-range resolutions of hundreds of meters, and this degraded as the distance between the sensor and the ground increased. While larger antennas improved resolution, it is not possible to build antennas large enough to provide good cross-range resolution for real-aperture radars.

The SAR technique, invented in the early 1950s, overcomes this problem by using the flight direction of the sensor to simulate, or synthesize, a large antenna. The individual transmit and receive cycles of the SAR imaging operation are completed from different locations as the sensor moves. The locations are treated as array elements of a single long antenna strung out along the flight direction. This SAR "trick" uses the long synthesized aperture to achieve fine cross-range resolution while the smaller physical aperture provides for a wide field of view.

Modern space-based commercial SAR systems, such as Cosmo Skymed, RADARSAT2 and TerraSAR-X, orbiting at approximately seven kilometers per second, and imaging for two-and-a-half seconds in high-resolution mode, have a synthetic aperture of 17.5 kilometers. A physical antenna of that size is inconceivable.Radar imaging systems can image through almost any weather condition, and they have several other useful remote sensing capabilities. In particular, the precise measurement of phase, which is fundamental to SAR, is simply not available to passive remote sensing systems. Despite the fact that SAR imaging is well outside the human experience, the opportunities it offers are powerful and far-reaching. We look forward to the next generation of scientists, engineers, and innovators to unleash the full potential of a technology that was invented more than 60 years ago.

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Electronic Engineering

posted 1 week 2 days ago

Amplifiers can also be categorized by the way they amplify the input signal.

Power amplifier

A power amplifier is an amplifier designed primarily to increase the power available to a load. In practice, amplifier power gain depends on the source and load impedances, as well as the inherent voltage and current gain.

 A radio frequency (RF) amplifier design typically optimizes impedances for power transfer, while audio and instrumentation amplifier designs normally optimize input and output impedance for least loading and highest signal integrity.

An amplifier that is said to have a gain of 20 dB might have a voltage gain of 20 dB and an available power gain of much more than 20 dB (power ratio of 100)—yet actually deliver a much lower power gain if, for example, the input is from a 600 ohm microphone and the output connects to a 47 kilohm input socket for a power amplifier. In general the power amplifier is the last 'amplifier' or actual circuit in a signal chain (the output stage) and is the amplifier stage that requires attention to power efficiency.

Efficiency considerations lead to the various classes of power amplifier based on the biasing of the output transistors or tubes: see power amplifier classes below.

Power amplifiers by application

·         Audio power amplifiers: typically used to drive loudspeakers, will often have two output channels and deliver equal power to each

·         RF power amplifier—typical in transmitter final stages (see also: Linear amplifier)

·         Servo motor controllers: amplify a control voltage where linearity is not important

·         Piezoelectric audio amplifier—includes a DC-to-DC converter to generate the high voltage output required to drive piezoelectric speakers

Power amplifier circuits

Power amplifier circuits include the following types:

·         Vacuum tube/valve, hybrid or transistor power amplifiers

·         Push-pull output or single-ended output stages

Operational amplifiers (op-amps)

An LM741 general purpose op-amp

Main articles: Operational amplifier and Instrumentation amplifier

An operational amplifier is an amplifier circuit which typically has very high open loop gain and differential inputs. Op amps have become very widely used as standardized "gain blocks" in circuits due to their versatility; their gain, bandwidth and other characteristics can be controlled by feedback through an external circuit. Though the term today commonly applies to integrated circuits, the original operational amplifier design used valves, and later designs used discrete transistor circuits.

Differential amplifiers

Main article: Fully differential amplifier

A fully differential amplifier is similar to the operational amplifier, but also has differential outputs. These are usually constructed using BJTsor FETs.

A differential amplifier is the first stage of an op-amp, a differential amplifier consists of two transistors which are emitter coupled. Types of differential amplifiers:

·         Differential mode

Vd= V1-V2

·         Common mode

It is the average between the input voltages V2 and V1 Vc=V1+V2/2


Distributed amplifiers

Main article: Distributed amplifier

These use balanced transmission lines to separate individual single stage amplifiers, the outputs of which are summed by the same transmission line. The transmission line is a balanced type with the input at one end and on one side only of the balanced transmission line and the output at the opposite end is also the opposite side of the balanced transmission line. The gain of each stage adds linearly to the output rather than multiplies one on the other as in a cascade configuration. This allows a higher bandwidth to be achieved than could otherwise be realized even with the same gain stage elements.

Switched mode amplifiers

These nonlinear amplifiers have much higher efficiencies than linear amps, and are used where the power saving justifies the extra complexity. Class-D amplifiers are the main example of this type of amplification



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Electronic Engineering

posted 1 week 3 days ago

RS flip flops find uses in many applications in logic or digital electronic circuitry. They provide a simple switching function whereby a pulse on one input line of the flip flop sets the circuit in one state. Further pulses on this line have no effect until the R-S flip flop is reset. This is accomplished by a pulse on the other input line. In this way the R S flip flop is toggled between two states by pulses on different lines.

Although chips are available with R-S functions in them, it is often easier to create an R-S flip flop from spare gates that may already be available on the board, or on a breadboard circuit using a chip that may be to hand. To make an R S flip flop, it simple requires either two NAND gates or two NOR gates.

Using two NAND gates and active low R S flip flop is produced. In other words low going pulses active the flip flop. As it can be seen from the circuit below, the two incoming lines are applied, one to each gate. The other inputs to each of the NAND gates are taken from the output of the other NAND gate.

It can be seen from the waveform diagram that a low going pulse on input A of the flip flop forces the outputs to change, C, going high and D going low. A low going pulse on input B then changes the state, with C going low and D going high.


An R S flip flop using two NAND gates


The circuit for the NOR version of the circuit is exceedingly similar and performs the same basic function. However using the NOR logic gate version of the R S flip flop, the circuit is an active high variant. In other words the input signals need to go high to produce a change on the output. This may determine the choice of integrated circuit that is used. Although the NAND gate version is probably more widely used, there are many instances where the NOR gate circuit is of value.

An R S flip flop using two NOR gates


These circuits are widely used in many electronic logic circuit applications. There are also contained within many integrated circuits where they are a basic building block. As such the R S flip flop is an exceedingly popular circuit.

One useful application for a simple R S flip flop is as a switch de-bounce circuit. When any mechanical switch makes or breaks contact, the connection will make and break several times before the full connection is made or broken. While for many applications this may not be a problem, it is when the switch interfaces to logic circuitry. Here a series of pulses will pass into the circuit, each one being captured and forming a pulse. Dependent upon the circuit this may appear as a series of pulses, and falsely triggering circuits ahead of time.



An R S flip flop used as a de-bounce circuit


It is possible to overcome this problem using a simple RS flip flop. By connecting the switch as shown below, the flip flop will change on the first sign of contact being made. Further pulses will not alter the output of the circuit. Only when the switch is turned over to the other position will the circuit revert to the other state. In this way a simple two gate circuit can save the problems of de-bouncing the switch in other ways.

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Electronic Engineering

posted 1 week 3 days ago

A logic gate is an elementary building block of a digital circuit. Most logic gates have two inputs and one output. At any given moment, every terminal is in one of the two binary conditions low (0) or high (1), represented by different voltage levels. The logic state of a terminal can, and generally does, change often, as the circuit processes data. In most logic gates, the low state is approximately zero volts (0 V), while the high state is approximately five volts positive (+5 V).

There are seven basic logic gates: AND, OR, XOR, NOT, NAND, NOR, and XNOR.

The AND gate is so named because, if 0 is called "false" and 1 is called "true," the gate acts in the same way as the logical "and" operator. The following illustration and table show the circuit symbol and logic combinations for an AND gate. (In the symbol, the input terminals are at left and the output terminal is at right.) The output is "true" when both inputs are "true." Otherwise, the output is "false."


AND gate

Input 1

Input 2
















The OR gate gets its name from the fact that it behaves after the fashion of the logical inclusive "or." The output is "true" if either or both of the inputs are "true." If both inputs are "false," then the output is "false."



OR gate

Input 1

Input 2

















The XOR ( exclusive-OR ) gate acts in the same way as the logical "either/or." The output is "true" if either, but not both, of the inputs are "true." The output is "false" if both inputs are "false" or if both inputs are "true." Another way of looking at this circuit is to observe that the output is 1 if the inputs are different, but 0 if the inputs are the same.


XOR gate

Input 1

Input 2

















A logical inverter , sometimes called a NOT gate to differentiate it from other types of electronic inverter devices, has only one input. It reverses the logic state.


Inverter or NOT gate








The NAND gate operates as an AND gate followed by a NOT gate. It acts in the manner of the logical operation "and" followed by negation. The output is "false" if both inputs are "true." Otherwise, the output is "true."


NAND gate

Input 1

Input 2














The NOR gate is a combination OR gate followed by an inverter. Its output is "true" if both inputs are "false." Otherwise, the output is "false."


NOR gate

Input 1

Input 2















The XNOR (exclusive-NOR) gate is a combination XOR gate followed by an inverter. Its output is "true" if the inputs are the same, and"false" if the inputs are different.

XNOR gate

Input 1

Input 2















Using combinations of logic gates, complex operations can be performed. In theory, there is no limit to the number of gates that can be arrayed together in a single device. But in practice, there is a limit to the number of gates that can be packed into a given physical space. Arrays of logic gates are found in digital integrated circuits (ICs). As IC technology advances, the required physical volume for each individual logic gate decreases and digital devices of the same or smaller size become capable of performing ever-more-complicated operations at ever-increasing speeds.

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Electronic Engineering

posted 1 week 3 days ago

A circuite that changes a code into a set of signals is called decode circuit. It decoded encoded data, but we will begin our study of encoders and decoders with decoders because they are simpler to design.

A common type of decoder is the line decoder which takes an n-digit binary number and decodes it into 2ndata lines. The simplest is the 1-to-2 line decoder. The truth table is

A is the address and D is the dataline. D0 is NOT A and D1 is A. The circuit looks like

Only slightly more complex is the 2-to-4 line decoder. The truth table is

Developed into a circuit it looks like


Larger line decoders can be designed in a similar fashion, but just like with the binary adder there is a way to make larger decoders by combining smaller decoders. An alternate circuit for the 2-to-4 line decoder is


Replacing the 1-to-2 Decoders with their circuits will show that both circuits are equivalent. In a similar fashion a 3-to-8 line decoder can be made from a 1-to-2 line decoder and a 2-to-4 line decoder, and a 4-to-16 line decoder can be made from two 2-to-4 line decoders.
You might also consider making a 2-to-4 decoder ladder from 1-to-2 decoder ladders. If you do it might look something like this:


For some logic it may be required to build up logic like this. For an eight-bit adder we only know how to sum eight bits by summing one bit at a time. Usually it is easier to design ladder logic from boolean equations or truth tables rather than design logic gates and then “translate” that into ladder logic.
A typical application of a line decoder circuit is to select among multiple devices. A circuit needing to select among sixteen devices could have sixteen control lines to select which device should “listen”. With a decoder only four control lines are needed.


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Electronic Engineering

posted 1 week 3 days ago
Operational Amplifiers are most stable and most high gain DC difference Amplifiers in the world.
Amplifiers are lacking in capacitive coupling between their various amplifying stages, they can only handles signals between the ranges of 0 to 100 kHz.

This is the symbol of OA(Operational Amplifier). Here we can she two inputs are there. First one is inverting and second one is non-inverting.  Here there is no significance of applied input signal.
The output signal (voltage), vo, is given by: 

vo = A(v+ - v-)

v+ and v- are the signals applied to the non-inverting and to the inverting input, respectively. Α represents the open loop gain of the OA. A is infinite for the ideal amplifier, whereas for the various types of real OAs, it is usually within the range of 104 to 106.

OAs require two power supplies to operate, supplying a positive voltage (+V) and a negative voltage (-V) with respect to circuit common. This bipolar power supply allows OAs to generate output signals (results) of either polarity.
The output signal (vo) range is not unlimited. The voltages of the power supplies determine its actual range. Thus, a typical OA fed with -15 and +15 V, may yield a vo within the (approximately) -13 to +13 V range, called operational range.
Any result expected to be outside this range is clipped to the respective limit, and OA is in a saturation stage.
The connections to the power supplies and to the circuit common symbols, shown in Figure 1, hereafter will be implied, and they will be not shown in the rest of the circuits for simplicity.
Because of their very high open loop gain, OAs are almost exclusively used with some additional circuitry (mostly with resistors and capacitors), required to ensure a negative feedback loop.
Through this loop a tiny fraction of the output signal is fed back to the inverting input. The negative feedback stabilizes the output within the operational range and provides a much smaller but precisely controlled gain, the so-called closed loop gain.
Circuits of OAs have been used in the past as analog computers, and they are still in use for mathematical operations and modification of the input signals in real time.
A large variety of OAs is commercially available in the form of low cost integrated circuits.
There is a plethora of circuits with OAs performing various mathematical operations. Each circuit is characterized by its own transfer function, i.e. the mathematical equation describing the output signal (vo) as a function of the input signal (vi) or signals (v1, v2, …, vn).
Generally, transfer functions can be derived by applying Kirchhoff’s rules and the following two simplifying assumptions:
#1. The output signal (vo) acquires a value that (through the feedback circuits) practically equates the voltages applied to both inputs, i.e. v+ ≈ v-.
#2. The input resistance of both OA inputs is extremely high(usually within the range 106-1012 MΩ, for the ideal OA this is infinite), thus no current flows into them.
Inverting Amplifier
The basic circuit of the inverting amplifier is shown in Picture 2.

The transfer function is derived as follows: Considering the arbitrary current directions we have:

 i1 = (vi - vs)/Ri   and   i2 = (vs - vo)/Rf

The non-inverting input is connected directly to the circuit common

(i.e. v+ = 0 V),

therefore (considering simplifying assumption #1) 

vs = v- = 0 V,


i1 = vi/Ri   and   i2 = - vo/Rf

Since there is no current flow to any input (simplifying assumption #2), it is

 i1 = i2

Therefore, the transfer function of the inverting amplifier is

vo = -(Rf/Ri)vi

Thus, the closed loop gain of the inverting amplifier is equal to the ratio of Rf (feedback resistor) over Ri (input resistor). This transfer function describes accurately the output signal as long as the closed loop gain is much smaller than the open loop gain A of the OA used (e.g. it must not exceed 1000), and the expected values of voare within the operational range of the OA.


Summing Amplifier

The summing amplifier  is a logical extension of the previously described circuit, with two or more inputs. Its circuit is shown in Picture 3.


The transfer function of the summing amplifier (similarly derived) is:

 vo = -(v1/R1  +  v2/R2  +  …  +  vn/Rn)Rf

Thus if all input resistors are equal, the output is a scaled sum of all inputs, whereas, if they are different, the output is a weighted linear sum of all inputs.
The summing amplifier is used for combining several signals. The most common use of a summing amplifier with two inputs is the amplification of a signal combined with a subtraction of a constant amount from it (dc offset).

Difference amplifier

Difference amplifier precisely amplifies the difference of two input signals. Its typical circuit is shown in Picture 4.  


Ri = RiőĄ and Rf = RfőĄ,

then the transfer function of the difference amplifier is:

vo = (v2 - v1) Rf/Ri

The difference amplifier is useful for handling signals referring not to the circuit common, but to other signals, known as floating signal sources. Its capability to reject a common signal makes it particularly valuable for amplifying small voltage differences contaminated with the same amount of noise (common signal).
In order for the difference amplifier to be able to reject a large common signal and to generate at the same time an output precisely proportional to the two signals difference, the two ratios p = Rf/Ri and q = RfőĄ/RiőĄ must be precisely equal, otherwise the signal output will be:

vo = [q(p+1)/(q+1)]v2 - pv1



The differentiator generates an output signal proportional to the first derivative of the input with respect to time. Its typical circuit is shown in Picture 5.

The transfer function of this circuit is

vo = -RC(dvi/dt)

Obviously, a constant input (regardless of its magnitude) generates a zero output signal. A typical usage of the differentiator in the field of chemical instrumentation is obtaining the first derivative of a potentiometric titration curve for the easier location of the titration final points (points of maximum slope).



The integrator generates an output signal proportional to the time integral of the input signal. Its typical circuit is shown in Picture 6


 vo = -(1/RC)∫vi(t)dt

The output remains zero as far as switch S remains closed. The integration starts (t = 0) when S opens. The output is proportional to the charge accumulated in capacitor C, which serves as the integrating device. A typical application of the (analog) integrator in chemical instrumentation is the integration of chromatographic peaks, since its output will be proportional to the peak area.  
If the input signal is stable then the output from the integrator will be given by the equation

vo = -(vi/RC) t

i.e. the output signal will be a voltage ramp. Voltage ramps are commonly used for generating the linear potential sweep required in polarography and many other voltammetric techniques.


This easy to use applet simulates the operation of the aforementioned circuits of operational amplifiers. The actual circuit is selected by the row of 5 “radio buttons” found on the lower part of the applet. In order to make the simulation more realistic, the operational range of all circuits is between -15 to +15 V. Output signals outside this range are “clipped” to the respective limit and the indication “Saturation” appears.
The magnitude of input signals (v1, v2) can be adjusted by the two scrollbars shown on the left side of the screen. The signal range (-2/+2 V,  -20/+20 V) is selected by the corresponding radio buttons.
The values of resistors (in kΩ) and capacitors (in μF) can be freely selected by the user.
The output signal (vo) is monitored by a simulated “digital voltmeter” and an “analog voltmeter”, as well, shown on the right side of the applet screen. The range of the scale of the later (-0,2/+0,2 V, -2,0/+2,0 V, -20/+20 V) can be selected using the corresponding radio buttons. The analog voltmeter is particularly useful for monitoring the time-depended signals of the differentiator and the integrator circuits.
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Electronic Engineering

posted 2 weeks 5 days ago
An analogue signal uses some attribute of the medium to convey the signals information. For example, an aneroid barometer uses theangular position of a needle as the signal to convey the information of changes inatmospheric pressure.[2] Electrical signals may represent information by changing their voltage, current, frequency, or total charge. Information is converted from some other physical form (such as sound, light, temperature, pressure, position) to an electrical signal by a transducer which converts one type of energy into another (e.g. a microphone).[3]

The signals take any value from a given range, and each unique signal value represents different information. Any change in the signal is meaningful, and each level of the signal represents a different level of the phenomenon that it represents. For example, suppose the signal is being used to represent temperature, with one volt representing one degree Celsius. In such a system 10 volts would represent 10 degrees, and 10.1 volts would represent 10.1 degrees.

Another method of conveying an analogue signal is to use modulation. In this, some base carrier signal has one of its properties altered:amplitude modulation (AM) involves altering the amplitude of a sinusoidal voltage waveform by the source information,frequency modulation (FM) changes the frequency. Other techniques, such as phase modulation or changing the phase of the carrier signal, are also used.[4]

In an analogue sound recording, the variation in pressure of a sound striking a microphonecreates a corresponding variation in the current passing through it or voltage across it. An increase in the volume of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same waveform or shape.

Mechanical, pneumatic, hydraulic and other systems may also use analogue signals.

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Electronic Engineering

posted 2 weeks 5 days ago
An analogue signal uses some attribute of the medium to convey the signals information. For example, an aneroid barometer uses theangular position of a needle as the signal to convey the information of changes inatmospheric pressure.[2] Electrical signals may represent information by changing their voltage, current, frequency, or total charge. Information is converted from some other physical form (such as sound, light, temperature, pressure, position) to an electrical signal by a transducer which converts one type of energy into another (e.g. a microphone).[3]

The signals take any value from a given range, and each unique signal value represents different information. Any change in the signal is meaningful, and each level of the signal represents a different level of the phenomenon that it represents. For example, suppose the signal is being used to represent temperature, with one volt representing one degree Celsius. In such a system 10 volts would represent 10 degrees, and 10.1 volts would represent 10.1 degrees.

Another method of conveying an analogue signal is to use modulation. In this, some base carrier signal has one of its properties altered:amplitude modulation (AM) involves altering the amplitude of a sinusoidal voltage waveform by the source information,frequency modulation (FM) changes the frequency. Other techniques, such as phase modulation or changing the phase of the carrier signal, are also used.[4]

In an analogue sound recording, the variation in pressure of a sound striking a microphonecreates a corresponding variation in the current passing through it or voltage across it. An increase in the volume of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same waveform or shape.

Mechanical, pneumatic, hydraulic and other systems may also use analogue signals.

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