What is a Digital Oscilloscopes??

Oscilloscopes are one of the basic requirement for any individual or firm involved with electronics. An oscilloscope which is also called as scope, is a type of electronic test equipment that allows signal voltages to be viewed, usually as a 2-D graph of one or more electrical potential differences (vertical axis) plotted as a function of time or of some other, voltage (horizontal axis).

It is a device with a wide array of uses, but mainly used to measures electrical signals, these signals are then represented in an interpretable and measurable format. For years, analogue oscilloscopes have provided this function. In modern times though, the more technologically advanced digital oscilloscope has replaced it.

Oscilloscopes

A digital oscilloscope (DSO) depicts the electrical signals in the form of a graphical illustration.A DSO measures the signal, and then converts that measurement into a digital format using an ADC converter, after which the data measured is depicted as a digital waveform representation. A large variety of oscilloscopes are available in a range of sizes from the more traditional bench oscilloscopes to lightweight, portable oscilloscopes which are usually battery powered. 

DSO have a wider range of functions than their analog counterparts which includes the ability to not just measure waveforms, but display them, store them, provide waveform processing, analysis and more. In general, DSO comes equipped with multiple input slots too, which allows the oscilloscope to make simultaneous readings of different devices simultaneously.

Applications of digital oscilloscopes
Due to their flexibility and resourcefulness, digital oscilloscopes are used in a variety of vocations and industries. Here are some of the applications of oscilloscopes.

• Oscilloscopes are used in the automotive field to assess the amount of vibrations a vehicle is causing, which helps the mechanic or manufacturer determine how effective the damping on the vehicle is, or if there are any structural defects.
• Another popular use of oscilloscopes is to measure seismic activity such as earthquakes, tremors and the shifting of seismic plates. Scientists and researchers working in the study of seismology find use for digital oscilloscopes regularly.
• In the world of music and sound, oscilloscopes are used to calculate the vibrating frequency and strength of sound waves. This helps them to determine the quality and reach of the audio, and is used in a variety of scenarios such as live shows, audio recording, television 
• Oscilloscopes also find function in the area of electricity and electronics. The quality and proficiency of power-based machines and systems are measured using oscilloscopes. Digital oscilloscopes are also used to trouble shoot such devices, as it can determine if there are issues in the flow of electricity within the devices.
• The most widely recognized use of an oscilloscope is in ECG or electrocardiography machines. Commonly seen in hospitals and used to measure the patient’s heart-rate, ECG machines are also used on pregnant women to measure the heartbeat of their infants.

The price of a DSO depends upon its functionality. The more high-end devices such as 6 GHz oscilloscopes and above can be quite expensive to purchase new, and can be rented from electronics test and measurement suppliers like Tektronix, TRS RenTelco, Rohde & Schwarz, Teledyne LeCroy, Keysight and others who offer rent, lease and sale options on this equipment. Although, trade of used digital oscilloscopes also occurs across the nation, meaning cheaper, second-hand alternatives can be found based on the buyer’s budget.

Source: R&D Magzine

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How to find DC and AC equivalents of BJT amplifier circuit

BJT (Bipolar Junction Transistor) is usually used in transistor circuits for amplification of voltage or current. It operates with both AC and DC voltages. AC signal is the signal which is amplified and the DC voltage is used for biasing of the transistor. Since the the components behave differently for DC and AC signals, therefore different methods are used for the analysis of the circuit.

The simplest and most widely used method is using the DC and AC equivalents. In this method the original amplifier circuit is converted to DC and AC equivalents and then the voltages and currents in both the circuits are calculated using KCL( Kirchoffs current law) or KVL (Kirchoffs voltage law) and then using the superposition theorem the final values are obtained.

Additional information

KCL: The algebraic sum of currents in a network of conductors meeting at a point is zero.

KVL: The sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop.

Superposition theorem: For a linear system the response (voltage or current) in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, where all the other independent sources are replaced by their internal impedances.

Simple BJT amplifier circuit

Source: www.pcbheaven.com

DC Equivalent

Steps:

• All the capacitors in the circuit are replaced by an open circuit.
• The AC sources present in the circuit are grounded.

Source: www.pcbheaven.com

With reference to the above given circuit, the capacitors Cin and Cout becomes open and the Input AC source is grounded.

 Simplified circuit :

Source: www.pcbheaven.com

AC equivalent

Steps:

• All the capacitors are replaced by short circuit.
• The DC sources present in the circuit are grounded.

Source: www.pcbheaven.com

With reference to the original amplifier circuit, the capacitors Cin and Cout becomes short and the DC source Vcc gets grounded.

Simplified circuit:

Source: www.pcbheaven.com

Since the original circuit is converted to its AC and DC equivalent, hence it is ready for analysis.

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Radio frequency data capacity can be doubled using the new tchnology

In Columbia Engineering a team of researchers has invented a technology—full-duplex radio integrated circuits (ICs)—which can be implemented in nanoscale CMOS (Complementary metal-oxide semiconductor is a  battery-powered memory chip in computers that stores startup information. Computer's basic input/output system (BIOS) uses this information while starting it), to enable simultaneous transmission and reception at the same frequency in a wireless radio. Until now, this considered to be impossible because transmitters and receivers either work at different times or at the same time but at different frequencies. The Columbia team, led by Electrical Engineering Assoc. Professor Harish Krishnaswamy, is the first to demonstrate an IC that can accomplish this.

CoSMIC (Columbia high-Speed and Mm-wave IC) Lab full-duplex transceiver IC that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio. 

Krishnaswamy said that "By leveraging our new technology, networks can effectively double the frequency spectrum resources available for devices like smartphones and tablets."In the era of big data, the frequency spectrum crisis is one of the biggest challenges researchers are grappling with and it is clear that today's wireless networks will not be able to support tomorrow's data deluge. Today's standards, such as 4G/LTE, already support 40 different frequency bands, and there is no space left at radio frequencies for future expansion. At the same time, the grand challenge of the next-generation 5G network is to increase the data capacity by 1,000 times.

So the ability to have a transmitter and receiver that use the same frequency has the potential to double the data capacity of today's networks. Krishnaswamy notes that other research groups and startup companies have demonstrated the theoretical feasibility of simultaneous transmission and reception at the same frequency, but no one has yet been able to build tiny nanoscale ICs with this capability. "Our work is the first to demonstrate an IC that can receive and transmit simultaneously," he says. "Doing this in an IC is critical if we are to have widespread impact and bring this functionality to handheld devices such as cellular handsets, mobile devices such as tablets for WiFi, and in cellular and WiFi base stations to support full duplex communications." he added.

The greatest challenge faced by the team was that the full duplex was cancelling the transmitter's echo which is same as trying to listen to someone's whisper from far away while at the same time someone else is yelling while standing next to you. If you can cancel the echo of the person yelling, you can hear the other person whispering.

Jin Zhou, Krishnaswamy's PhD student and the paper's lead author explains that "If everyone could do this, everyone could talk and listen at the same time, and conversations would take half the amount of time and resources as they take right now,". "Transmitter echo or 'self-interference' cancellation has been a fundamental challenge, especially when performed in a tiny nanoscale IC, and we have found a way to solve that challenge." he added.

Krishnaswamy and Zhou plan next to test a number of full-duplex nodes to understand what the gains are at the network level. "We are working closely with Electrical Engineering Assoc. Professor Gil Zussman's group, who are network theory experts here at Columbia Engineering," Krishnaswamy added. "It will be very exciting if we are indeed able to deliver the promised performance gains."

Source:R&D Magazine 

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Artificial skin developed that can be used for camouflaging

A new chameleon like artificial skin was developed that can change its colour depending upon how much force is applied.Engineers from the university of California at Berkeley have created it.This new material is incredibly thin and offers many colours, intriguing possibilities for an entirely new class display tech, colour shifting camouflage, and sensors that can detect otherwise imperceptible defects in buildings

"This is the first time anybody has made a flexible chameleon like skin that can change colour simply by flexing it," said Connie Chang-Hasnain, a member of the Berkely team and co-author on paper published in Optica. By precisely etching tiny features-smaller than a wavelength of light-onto a silicon film one thousand times thinner than a human hair, they were able to select the range of colours the material would reflect, depending on how it was flexed and bent.

WORKING

The colours we typically see in paints, fabrics and other natural substances occur when white, broad spectrum light strikes their surfaces. the unique chemical composition of each surface then absorbs various bands, or wavelengths of light. Those that aren't absorbed are reflected back, with shorter wavelengths giving objects a blue hue and longer wavelengths appearing redder and the entire rainbow of possible combinations in between changing the colour of a surface, such as the leaves on the trees in autumn, requires a change in chemical make-up.

Recently engineers and scientists have been exploring another approach, one that would create designer colours without the use of chemical dyes and pigments, rather than controlling the chemical composition of a material, it's possible to control the surface features on the tiniest of scales so they interact and reflect particular wavelengths of light. This type of structural colour is much less common in nature, but is used by some butterflies and beetles to create a particular iridescent display of colour.

Controlling light with structures rather than traditional optics is not new. In astronomy, for example evenly space slits known as diffraction gratings are are routinely used to direct light and spread it into its component colours. Efforts to control colour this technique, however, have proved impractical because the optical losses are simply too great.

The authors of the paper applied a similar principle, though with a radically different design, to achieve the colour control they were looking for. In place of slits etched rows of ridges onto a single, thin layer of silicon. Rather than spreading the light into a complete rainbow, however, these ridges (bars) reflect  a very specific wavelength of light, by tuning the spaces between the bars, it's possible to select the specific colour to be reflected.Unlike the slits in a diffraction grating, the silicon bars were extremely efficient and readily reflected the frequency of light they were turned to.

FLEXIBILITY

Since the spacing or period of the bars is the key to controlling the colour they reflect, the researchers realised it would be possible to subtly shift the period and therefore the colour by flexing or bending the material. "If you have a surface with very precise structures, spaced so they can interact with a specific wavelength of light, you can change its properties and how it interacts with light by changing its dimensions," said Chang-Hasnain.

Earlier efforts to develop a flexible, colour shifting surface fell short on a number of fronts. Metallic surfaces, which are easy to etch, were inefficient, reflecting only a portion of the light they received. Other surfaces were too thick, or too rigid, preventing them from being flexed with control. The Berkeley researchers were able to over come both these hurdles by forming their grating bars using a semiconductor layer of silicon approximately 120 nanometers thick. It's flexibility was imparted by embedding the silicon bars into a flexible layer of silicone. As the silicone was bent or flexed, the period of the grating spacings responded in kind.

The semiconductor material also allowed the team to create a skin that was incredibly thin, perfectly flat and easy to manufacture with the desired surface properties. This produces materials that reflect precise and very pure colours and that are highly efficient, reflecting up to 83% of the incoming light. Their initial design, subjected to a change in period of a mere 25 nanometers, created brilliant colour that could be shifted from green to yellow, orange, and red across a 39 nanometer range of wavelengths. Future designs, the researchers believe, could cover a wider range of colours and reflect with more efficiency.

CHAMELEON SKIN

For this demonstration, the researchers created a one-centimeter square layer of colour-shifting silicon.Future developments would be needed to create a material large enough for commercial applications.

For consumers, this chameleon material could be used in a new class of display technologies, adding brilliant colour presentation to outdoor entertainment venues. It also may be possible to create an active camouflage on the exterior of the vehicles that would change colour to better match the surrounding environment.More day to day applications could include sensors that would change colour to indicate that structural fatigue was stressing critical components on bridges, buildings. or the wings of airplanes.    

Source: Mumbai mirror        

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All-new Apple's 12" MacBook

Apple took everyone by surprise by revealing a lot more than just Apple Watch details.The new MacBook was part of that surprise, bringing a reinvented MacBook that is thinner, and certainly more minimalistic than the popular MacBook Air.

The new MacBook has a 12-inch Retina display (2304x1440) with edge to edge glass and much thinner bezels. Apple claims that it is 24% thinner than the MacBook Air at 13.1mm and weighing in at 2 pounds.Apple also highlighted its success in selling products, saying that while the PC market overall is stagnant, Mac sales grew by 20% last year. While mentioning that portability is core in products like iPhone and iPad, the new MacBook is as closest as the company has got to the same philosophy on a full fledged PC. The new MacBook will be available in gold, silver and grey colour.

The redesigned MacBook is a unibody design with all metal, sporting a full sized keyboard and new trackpad technology. The keyboard has received a new typing mechanism that allows for the thin design, while decreasing wobbling. The trackpad is also new, with haptic feedback and force sensors, adding a new 'force click' option, so a deep press in the trackpad allows for different options depending on the software interface, just like what a right-click does.

Drawing another parallel to how iPads are built, the new MacBook is all battery inside. The logic board is tiny, even when compared to the 11" MacBook Air's, it's 67% smaller. Apple claims 9-hour battery life when web browsing, and up to 10 hours of movie playback on iTunes.

Technical specs:

There will be two models of the new MacBook when it goes on sale next April 10.

• Both models share the same 12" Retina screen and are fanless.
•  $1299  will get you a 1.1GHz dual-core Intel M processor, Intel HD 5300 graphics, 8GB RAM and a 256GB SSD.
• $1599,will get you the same machine, but with a slightly faster 1.2GHz Core M CPU and a 512GB SSD. 

As rumoured, USB-C is the only port in the system. The reversible USB port will be used to power the new MacBook as well as provide connectivity for DisplayPort, HDMI, and VGA, assumingly with required adapters depending on your needs.

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Future missions to Mars may not be a one-way trip

Martian colonists could use an innovative new technique to harvest energy from carbon dioxide thanks to research pioneered at Northumbria and Edinburgh Universities. The technique, has been proven for the first time by researchers at the two universities and the work has been published in the prestigious journal Nature Communications.

The research proposes a new kind of engine for producing energy based on the Leidenfrost effect(phenomenon which happens when a liquid comes into near contact with a surface much hotter than its boiling point). This effect is commonly seen in the way water appears to skitter across the surface of a hot pan, but it also applies to solid carbon dioxide, commonly known as dry ice. Blocks of dry ice are able to levitate above hot surfaces protected by a barrier of evaporated gas vapour.

Northumbria's research proposes using the vapour created by this effect to power an engine. This is the first time the Leidenfrost effect has been adapted as a way of harvesting energy.

The technique has exciting implications for working in extreme and alien environments, such as outer space, where it could be used to make long term exploration and colonisation sustainable by using naturally occurring solid carbon dioxide as a resource rather than a waste product. If this could be realized, then future missions to Mars won't be one way after all.

Dry ice may not be abundant on Earth, but increasing evidence from NASA's Mars Reconnaissance Orbiter(MRO) suggests it may be a naturally occurring resource on Mars as suggested by the seasonal appearance of gullies on the surface of the red planet. If utilized in a Leidenfrost based engine dry ice deposits could provide the means to create future power stations on the surface of Mars.

Rodrigo Ledesma-Aguilar one of the co-authors of Northumbria's research said that " Carbon dioxide plays a similar role on Mars as water does on Earth. It is a widely available resource which undergoes cyclic phase changes under the natural Martian temperature variations"."Perhaps future power stations on Mars will exploit such a resource to harvest energy as dry ice blocks evaporate, or to channel the chemical energy extracted from other carbon based sources, such as methane gas" he added.

"One thing is certain, our future on other planets depends on our ability to adapt our knowledge to the constraints imposed by strange worlds, and to devise creative ways to exploit natural resources that do not naturally occur here on earth," he said. The team at Northumbria believe one of humanity's biggest challenges this century will be finding new ways to harvest energy, especially in extreme environments. It was this challenge which led them to develop their proposed Leidenfrost Engine.

"The working principle of a Leidenfrost based engine is quite distinct from steam based heat engines, the high pressure vapour layer creates freely rotating rotors whose energy is converted into power without the need of a bearing, thus conferring the new engine with low friction properties," explained Gary wells, co-author of the paper.
   

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Great future plans for QR codes

QR(quick response) code are those which are usually in black and white boxes that people scan with their mobile phones to download or to know more about something.The researchers from the  University of Connecticut says that these can even take care of national security.

Board of Trustees Distinguished Professor Bahram Javidi said that “An optical code or QR code can be manufactured in such a way that it is very difficult to duplicate,”. “But if you have the right keys, not only can you authenticate the chip, but you can also learn detailed information about the chip and what its specifications are" he added.


Used computer chips doesn't matter much when in the case of poor cell phone reception or an laptop computer crash in personal use, but the problem becomes exponentially more serious when counterfeit or hacked chips turn up in nation's military force.

Unlike commercial QR codes, Javidi’s little black and white boxes can be scaled as small as microns or a few millimeters and would replace the electronic part number that is currently stamped on most microchips.

Javidi also says that he can compress vital information about a chip i.e its functionality, capacity and part number, directly into the QR code so that it can be obtained by the reader without having access to the internet, and this is important in cybersecurity circles, because by linking to the Internet means great increase chances of hacking or corruption.

Javidi has also applied an optical imaging mask which scrambles the QR code design into a mass of black and white pixels which looks similar to the images seen on a broken television, to ensure proper security. He then added another layer of security through a random phase photon based encryption that turns the snowy image into a darkened night time sky with just a few random stars or dots of pixilated light.

The end result of all these layering is a highly secure, microscopic design that is next to impossible to duplicate. Only the individuals with special corresponding codes can decrypt the QR image.

Related posts:Super fast computers, Smartphones

Source:R&D Magazine 

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Exams to be given to get into engineering colleges?

In India many exams are conducted every year for engineering aspiring students to get into engineering colleges.The admissions will be completely based on the score you get in the entrance test and the marks obtained in 12th and 10th.

NATIONAL LEVEL ENGINEERING ENTRANCE EXAMS 

• JEE-MAINS(Previously AIEEE) – Standard means of entry to the National Institutes of Technology (NITs) across India with other reputed private as well as government universities including Delhi College of Engineering(DCE) and Netaji Subhas Institute of Technology, University of Delhi (NSIT).
• BITSAT – Standard means of entry to  BITS Pilani institutes across the country.
• VITEEE - mode of entry into campuses of VIT University.
• JEE-ADVANCED (previously IIT-JEE) – Standard exams for entry to the Indian Institutes of Technology (IITs). For giving this exam one has to first qualify in JEE-MAINS by obtaining the cut-off mark of the year.
• Manipal Universtiy, SRM, Jain University, KIIT, Amrita School of Engineering, Entrance Examinations- for entry into these reputed private Deemed Universities.

STATE LEVEL ENGINEERING ENTRANCE EXAMS

• EAMCET (Engineering,Agriculture and Medical Entrance Examination)
• Kerala-KEAM Entrance (Kerala Engineering Agricultural Medical)
• Karnataka CET
• Karnataka-COMEDK UGET (Engineering)
• Maharashtra Technical Common Entrance Test MT CET
• Delhi Technological University (DTU)
• IP University
• Jamia Millia Islamia
• West Bengal Joint Entrance Examination (WBJEE)

STATES/UNIVERSITIES/INSTITUTES CONSIDERING JEE-MAINS MARKS FOR ADMISSION

1.Haryana

2.Uttarakhand

3.Gujarat

4.Nagaland

5.Maharashtra

6.Odisha

7.Madhya Pradesh

8.Punjab Technical University, Jalandhar

9.Punjab Engineering College, Chandigarh

10.Indian Institute of Science, Banglore

11.Indian Institute of Space Technology, Thiruvanathapuram

12.Indraprastha Institute of Information Technology, Delhi

13.Delhi Technological University for Women, New Delhi

14.Delhi Technological University, Delhi

15.Indian Institute of Crop Processing Technology, Thanjavur 

16.Netaji Subhash Institute of Technology (under Delhi University)

Related posts:GATE(Graduate Aptitude Test in Engineering),Exam to be given to get into engineering colleges abroad

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What's engineering?

When a kid hears the word engineering the first thing that comes to his/her mind would be a person controlling an engine of a train.

SOURCE :www.exbury.co.uk

                                                                                                                                                                    But as we grow up the concept about engineers changes, people always confuse engineers with scientists they think that engineers and scientists do the same stuff ,but its not true.Scientists are the ones who comes up with different  theories whereas engineers are the ones who apply them, they often work together where scientists tell the engineers what to make and engineers tell them the constraints. They indeed are different, but they work close to each other and they need each others help to complete a task.

A person who has opted for engineering gets to do many amazing stuffs like:

1. It provides the platform for them to hone their skills at technical level.
2. It gives the opportunities to explore through many scientific possibilities.
3. It even gives them opportunities to get into a good company or to become an entrepreneur.

Engineering is a course where a person's career can easily flourish if he/she is really interested in it.

POPULAR STREAMS IN ENGINEERING

1. Computer Engineering
2. Aeronautical Engineering
3. Mechanical Engineering
4. Electrical Engineering
5. Electronics and Communication
6. Chemical Engineering
7. Civil Engineering And many more streams.

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