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Saturday 25 May 2013

Automotive Battery Charger Circuit Diagram With Working

A very simple battery charger circuit is described in this article, which uses just a single transistor for the voltage detection as well as for automatically disconnecting the battery from the supply when it gets fully charged.

Circuit Description

As shown in the diagram we can see a straightforward configuration where a single transistor is connected in it’s standard operating mode. 

The circuit functioning may be understood with the help of the following points:

Considering the battery to be charged is a 12 volt battery, we know that it is advised to charge the battery until it reaches between 13.5 and 14 volts.

The transistor base voltage is adjusted using the preset P1, such that the transistor just conducts and operates the relay at around 14 volts.

This adjustment becomes the high voltage trip point of the circuit and is used to switch OFF the charging voltage to the battery when it gets fully charged or its voltage reaches around 14 volts.

The lower trip point of the circuit cannot be adjusted as this circuit is too simple and does not incorporate the low voltage detection feature.

However the transistor is itself equipped with a switch OFF feature in case its base voltage becomes too low.

Typically a general purpose transistor like the one which is shown (BC547) when adjusted to switch ON at 14 volts may have the lower threshold of around 10 volts, when it might get just switched OFF.

This wide voltage difference between the high set threshold and the lower natural threshold is because of the involved big hysteresis with the design.

The lower threshold of 10 volts is dangerously low and we cannot wait for the circuit to restart the charging process until the battery voltage falls to this dangerous 10 volts level.

 Allowing the battery to discharge down to 10 volts can make the battery flat permanently and reduce its life.
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Therefore to eliminate this issue the circuit needed to somehow reduce the hysteresis level. This is done by introducing a couple of diodes at the emitter of the transistor.

We know that normally a 1N4007 diodes would drop around 0.7 volts across it and two if them would make a total of 1.4 volts.

By inserting the two diodes in series with the emitter of the transistor, we force the transistor to switch off 1.4 V earlier than its normal specified limit of 10 volts.

Therefore now the lower operating threshold of the circuit becomes 10 + 1.4 = 11.4 volts, which may be considered just OK for the battery and for the automatic restart of the charging process.

Having both the thresholds updated as per the standard charging requirements, we now have an automatic automotive battery charger that’s not only cheap to build but also smart enough to take care of the battery charge conditions very efficiently.


Parts List

R1 = 4K7

P1 = 10K preset,

T1 = BC547B,

Relay = 12V, 400 Ohms, SPDT,

TR1 = 0 - 14V, current 1/10th of the battery AH

Bridge diodes = Equal to the current rating of the transformer,

Emitter diodes = 1N4007,

C1 = 100uF/25V

Thursday 23 May 2013

How to Reset Your Forgotten Windows Password the Easy Way


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Forgetting your password is never any fun, but luckily there’s a really easy way to reset the password. All you need is a copy of the Windows installation disk and one simple command line trick.

Resetting Your Forgotten Windows Password

Boot off the Windows disk and select the “Repair your computer” option from the lower left-hand corner.
Follow through until you get to the option to open the Command Prompt, which you’ll want to select.
First you’ll want to type in the following command to backup the original sticky keys file:
copy c:\windows\system32\sethc.exe c:\
Then you’ll copy the command prompt executable (cmd.exe) over top of the sticky keys executable:
copy c:\windows\system32\cmd.exe c:\windows\system32\sethc.exe
Now you can reboot the PC.

Resetting the Password

Once you get to the log in screen, hit the Shift key 5 times, and you’ll see an administrator mode command prompt.
Now to reset the password—just type the following command, replacing the username and password with the combination you want:
net user geek MyNewPassword
That’s all there is to it. Now you can login.
Of course, you’ll probably want to put the original sethc.exe file back, which you can do by rebooting into the installation CD, opening the command prompt, and copying the c:\sethc.exe file back to c:\windows\system32\sethc.exe.

6 Types of Browser Errors While Loading Web Pages and What They Mean

404 PAGE NOT FOUND

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You’re guaranteed to stumble into an occasional error page while browsing the web. This guide will help you understand exactly what each error page means and what to do when you see them.
Note that each browser displays and words its error pages differently. A certificate error or malware warning looks different in each different browser, but the different types of error pages mean the same thing.

Certificate Error

An SSL certificate error or security certificate error indicates a problem with HTTPS encryption. You’ll only see this error when connecting to a website using HTTPS.
When using HTTPS encryption, websites present certificates to identify that they are legitimate. For example, Google.com has a security certificate issued by a trusted certificate authority. The certificate authority verifies that Google is the real owner of Google.com and is entitled to the certificate. When you connect to Google.com using HTTPS, Google presents this certificate. Your browser checks that the certificate was issued by a known legitimate certificate authority to verify you’re connecting to the real Google.com, not another server pretending to be Google.com.
When you see a certificate error, this indicates that you’re not necessarily connecting to the real, legitimate website. For example, if you try to access your bank’s website on a public Wi-Fi network and see this error, it’s possible that the network is compromised and someone is attempting to impersonate your bank’s website.
However, it’s also possible that a website failed to properly renew or configure its certificate. Either way, you shouldn't continue when you see this error message.

Phishing and Malware Warnings

Your browser will also display phishing (or “web forgery”) and malware warnings. Whether you use Firefox, Chrome, or Internet Explorer, your browser regularly downloads a list of dangerous websites. When you attempt to connect to a website on this list, you’ll see an error message.
Websites are placed on these lists because they contain malware or because they attempt to impersonate a real website to steal your passwords, credit card numbers, or other sensitive information.
In some cases, a website may temporarily be added to this list because it was compromised. When the website is fixed, it should be removed from this list. When you see this message, you shouldn't continue.

404 Not Found

You may see a variety of web server messages when accessing web pages. The most common one is “404 Not Found,” which means you’re trying to access a page that doesn't exist. Either the web page was removed or you were typing in an address and mistype it.
These error messages are generated by the remote web server and sent to your browser. If you see these, double-check the web page address you typed. If you clicked a link, the link was in error – or the page it points to has been removed.

Customized Error Pages

Website owners can customize the 404 Not Found and other error pages on their websites. For example, we have a special 404 Page Not Found error inspired by classic Mario games. These errors mean the same thing, but they’re generally customized to be more friendly and help you find what you’re looking for.

Server Not Found

A “Server not found” error in Firefox or “Google Chrome could not find [website.com]” message indicates that your browser could not find the website you’re trying to access.
Either you mistype a website address and you’re trying to access a website that doesn't exist, your DNS server is down, or your firewall, proxy, or other settings are reconfigure.

Unable to Connect

The “Unable to connect” error in Firefox or “Google Chrome could not connect to [website.com]” message looks similar to the “Server not found” message above, but each means something different.
if you see this message, your browser has successfully contacted its DNS servers and identified that there should be a website at the target location. However, your browser did not receive a response from the website’s servers when it tried to connect.
If you see this message, it’s possible that the website itself is down or experiencing problems. You may want to try Down For Everyone Or Just For Me, a website which tells you whether a website is down or if you just can’t access it. It’s also possible that your firewall, proxy, or other network settings are misconfigured.
Read More: How To Troubleshoot Internet Connection Problems

There are quite a few other errors you may come across, but these are the most common ones. With some knowledge of these errors, you should know what’s going on every time you bump into an error page on the web.

How To Create a Customized Windows 7 Installation Disc With Integrated Updates


How To Create a Customized Windows 7 Installation Disc With Integrated Updates


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Do you want to save time when installing Windows 7? You can create a customized installation disc and have it perform an installation without asking you questions, integrate updates and drivers, tweak Windows, and remove Windows components.
We’ll be using RT Se7en Lite for this – if you’ve used nLite with Windows XP or vLite with Windows Vista in the past, it works similarly. RT Se7en Lite is a sort of vLite or nLite for Windows 7.
Image Credit: bfishadow on Flickr

What You’ll Need

To do this, you’ll need Windows 7 installed on your computer. You’ll also need to download and install the Windows Automated Installation Kit (WAIK) for Windows 7 from Microsoft – RT Se7en Lite is a more user friendly frontend to WAIK.
WAIK is 1.7 GB, so the download may take a while if you have a slow Internet connection. After downloading it, extract it with a file extraction program such as 7-Zip.
Run the StartCD.exe file, select Windows AIK Setup, and follow the instructions on your screen to install Windows AIK.
You’ll also need a Windows 7 installation source – either a physical disc or ISO file.
Next, download and install RT Se7en Lite from here – it’s free and donation-supported. Download the appropriate version for your version of Windows — x86 if you’re using a 32-bit version of Windows or x64 if you’re using a 64-bit edition.

Using RT Se7en Lite

First, click the Browse button and provide your Windows 7 files – if you have an ISO file on your hard drive, click Select ISO file and navigate to it. If you have a Windows disc, insert the disk, click Select OS path, and navigate to the disc.
If you provide an ISO, you’ll have to specify an extraction path where the ISO’s files will be extracted to – you’ll need several gigabytes of space on your hard disk for this.
The files will be automatically extracted after you provide your ISO.
After selecting the edition of Windows 7 you’re customizing, RT Se7en Lite will load the image. If you have a Windows 7 disc without Service Pack 1 integrated, click the Slipstream Service Pack option in the “Select an image to configure” window and you’ll be able to integrate SP1.
Click over to the Task pane and select the tasks you want to perform after the image is loaded. You can manually check the check boxes or select a preset. Selecting one of the check boxes will activate the corresponding configuration pane at the left side of the window.
The integration pane allows you to integrate Windows updates, drivers, language packs, and even third-party applications into your installation disc. To integrate updates, you’ll have to download their installer files and load them into RT Seven Lite with the Add button.
On the Features Removal or Components tab, you can permanently remove components from your Windows installation disc and control which Windows features are installed by default. For example, you can remove the included games from your Windows installer disc, or force Windows to install the IIS web server by default.
The Tweaks tab allows you to customize the default settings for the Windows Control Panel, Desktop, Explorer, and a variety of other Windows components. You can even add custom registry settings to tweak other settings that aren't present in the list.
The Unattended section allows you to create an unattended installation disc – you provide answers to installation questions beforehand and Windows will install without asking you these questions during the installation process.
For example, you can enter your product key ahead of time so Windows won’t ask you for it. The other tabs allow you to control other settings – for example, selecting the hard disks that Windows will install on. If you complete enough of these settings, Windows will install automatically without asking you any questions during the installation, allowing you to perform an unattended Windows installation.
The Customization pane allows you to add custom screensavers, wallpapers, themes, documents, and even logon screens to your Windows 7 disc.
On the ISO Bootable pane, you can create a ISO image from your customized installation disc. You can also burn it to a DVD or copy it to a bootable USB drive.
RT Se7en Lite’s developers recommend booting your custom Windows 7 image in a virtual machine and installing it in the virtual machine before you use it on a physical computer, just to make sure everything is working properly.
You can use VirtualBox or VMware Player to do this – both are free.

Wednesday 22 May 2013

Stanford engineers monitor heart health using paper-thin flexible 'skin'

Engineers combine layers of flexible materials into pressure sensors to create a wearable heart monitor thinner than a dollar bill. The skin-like device could one day provide doctors with a safer way to check the condition of a patient's heart.
BY 

Most of us don't ponder our pulses outside of the gym. But doctors use the human pulse as a diagnostic tool to monitor heart health.
Zhenan Bao, a professor of chemical engineering at Stanford, has developed a heart monitor thinner than a dollar bill and no wider than a postage stamp. The flexible skin-like monitor, worn under an adhesive bandage on the wrist, is sensitive enough to help doctors detect stiff arteries and cardiovascular problems.
The devices could one day be used to continuously track heart health and provide doctors a safer method of measuring a key vital sign for newborn and other high-risk surgery patients.
"The pulse is related to the condition of the artery and the condition of the heart," said Bao, whose lab develops artificial skin-like materials. "The better the sensor, the better doctors can catch problems before they develop."

Your pulse

To find your pulse, press your index and middle finger into the underside of your opposite wrist. You should feel the steady rhythm of your heart as it pumps blood through your veins.
L.A. CiceroSkin-like heart monitor
This flexible skin-like heart monitor is small enough to wear under a bandage.
Each beat you feel is actually made up of two distinct peaks, even though you can't tell them apart with just your fingers. The first, larger peak is from your heart pumping out blood. Shortly after a heartbeat, your lower body sends a reflecting wave back to your artery system, creating a smaller second peak.
The relative sizes of these two peaks can be used by medical experts to measure your heart's health.
"You can use the ratio of the two peaks to determine the stiffness of the artery, for example," said Gregor Schwartz, a post-doctoral fellow and a physicist for the project. "If there is a change in the heart's condition, the wave pattern will change. Fortunately, when I tested this on myself, my heart looked fine."
To make the heart monitor both sensitive and small, Bao's team uses a thin middle layer of rubber covered with tiny pyramid bumps. Each mold-made pyramid is only a few microns across – smaller than a human red blood cell.
When pressure is put on the device, the pyramids deform slightly, changing the size of the gap between the two halves of the device. This change in separation causes a measurable change in the electromagnetic field and the current flow in the device.
The more pressure placed on the monitor, the more the pyramids deform and the larger the change in the electromagnetic field. Using many of these sensors on a prosthetic limb could act like an electronic skin, creating an artificial sense of touch.
When the sensor is placed on someone's wrist using an adhesive bandage, the sensor can measure that person's pulse wave as it reverberates through the body.
The device is so sensitive that it can detect more than just the two peaks of a pulse wave. When engineers looked at the wave drawn by their device, they noticed small bumps in the tail of the pulse wave invisible to conventional sensors. Bao said she believes these fluctuations could potentially be used for more detailed diagnostics in the future.

Blood pressure and babies

Doctors already use similar, albeit much bulkier, sensors to keep track of a patient's heart health during surgery or when taking a new medication. But in the future Bao's device could help keep track of another vital sign.
"In theory, this kind of sensor can be used to measure blood pressure," said Schwartz. "Once you have it calibrated, you can use the signal of your pulse to calculate your blood pressure."
This non-invasive method of monitoring heart health could replace devices inserted directly into an artery, called intravascular catheters. These catheters create a high risk of infection, making them impractical for newborns and high-risk patients.  Thus, an external monitor like Bao's could provide doctors a safer way to gather information about the heart, especially during infant surgeries.
Bao's team is working with other Stanford researchers to make the device completely wireless. Using wireless communication, doctors could receive a patient's minute-by-minute heart status via cell phone, all thanks to a device as thick as a human hair.
"For some patients with a potential heart disease, wearing a bandage would allow them to constantly measure their heart's condition," Bao said. "This could be done without interfering with their daily life at all, since it really just requires wearing a small bandage."
The team published its work in the May 12 edition of Nature CommunicationsThe team's research is supported by funding from the National Science Foundation and the Air Force Office of Scientific Research.


Inspirational Quotes- With Pics











Tuesday 21 May 2013

Intel picks science fair winners, awards $630,000 to genius high schoolers


Sara Volz, a 17-year-old high school student from Colorado, received top honors and a $100,000 check Tuesday at a science fair for pioneering a technique to dramatically boost oil yields from algae, a crucial step in the economically viable production of biofuel from the plants.
Her technique involves the use of a chemical to artificially select populations of algae cells with high oil content. She did all the work in a makeshift lab under her loft bed in Colorado Springs.

Volz, a senior from Cheyenne Mountain High School, was among 40 finalists who gathered in Washington, D.C., for the Intel Science Talent Search. The annual competition identifies some of the nation’s most promising young scientists and innovators.
The finalists were narrowed down from 300 semifinalists and more than 1,700 entrants from around the country. Participants in the 72-year-old competition have gone on to win seven Nobel Prizes and 11 MacArthur Foundation Fellowships, among other honors.
Second-place honors and $75,000 went to Jonah Kallenbach, 17, of Ambler, Pa., who built a computer-science tool for predicting protein binding for drug therapy. The tool may open the door to new treatments for diseases such as breast cancer, ovarian cancer and tuberculosis.
Third-place honors and $50,000 went to Adam Bowman, 17, of Brentwood, Tenn., who successfully designed and built a compact and inexpensive, low-energy, pulsed plasma device. The technique should allow plasma research to be conducted in small-scale operations and even high school labs. Plasma applications range from semiconductor manufacturing to nuclear physics.
The talent search is a program of the Society for Science and the Public, a non-profit organization that advocates for public engagement in scientific research and education. According to the Intel Foundation, the competition’s sponsor, the prizes are an investment in America’s future.
“It’s crucial to U.S. innovation to bring greater attention to math and science achievement, encourage more youth to embrace these fields, and demonstrate the impact these subjects have on our country’s future success,” Wendy Hawkins, Intel Foundation executive director, said in a news release.
Other top honors from the competition include:
4th place: Hannah Larson of Eugene, Ore., received a $40,000 award for her research of an abstract mathematical structure that’s important in many areas of theoretical physics and computer science.
5th place: Peter Kraft of Munster, Ind., received a $30,000 award for his synthesis of 10 new coordination polymers, which are massive molecules with complex network structures that have applications in gas purification and the storage of hydrogen in fuel cells.
6th place: Kensen Shi of College Station, Texas, received a $25,000 award for his development of a computer algorithm that makes it easier for a robot to avoid colliding with obstacles in its path.
7th place: Samuel Zbarsky of Rockville, Md., received a $25,000 award for his math research that could improve the efficiency of 3-D computer networks.
8th place: Brittany Wenger of Sarasota, Fla., received a $20,000 award for her development of an artificial neural network to help diagnose breast cancer using data from fine-needle biopsy samples.
9th place: Akshay Padmanabha of Collierville, Tenn., received a $20,000 award for his development of an algorithm that detects oncoming epileptic seizures.
10th place: Sahana Vasudevan of Palo Alto, Calif. received a $20,000 award for her math research that proved a new, generalized way to minimize an important function of arithmetic.

Student's self-driving car tech wins Intel science fair


When self-driving cars reach the masses, thanks may be due to a 19-year-old high-school student from Romania who developed an artificial intelligence that slashes the cost of the technology. He took top prize — a $75,000 scholarship — Friday at an international science and engineering fair.

Self-driving cars are nothing new. Tech giant Google, for example, has been working on one since 2010. But Google's uses technology that was developed without thinking about cost, prize winner Ionut Budisteanu explained.
"The most expensive thing from the Google self-driving car is the high resolution 3-D radar, so I was thinking how I could remove it," he told NBC News.
His solution relies on processing webcam imagery with artificial intelligence technology to pick out the curbs, lane markers, and even soccer balls that roll onto the road. This is coupled with data from a low-resolution 3-D radar that recognizes "big" objects such as other cars, houses, and trees.
All of this information is collected and processed real time by a suite of computers that, in turn, feed into a "supervisor" computer program that calculates the car's path and drives it down the road.
Budisteanu ran 50 simulations with his system and in 47 of them it performed flawlessly. In three, however, it failed to recognize some people who were 65 to 100 feet (20 to 30 meters) away. He said slightly higher-resolution 3-D radar should do the trick and still keep costs at a fraction of Google's.
Image of simulation
Intel
A simulation of the self-driving car technology powered by artificial intelligence.

The high-resolution 3-D radar used by Google, he noted, costs about $75,000. His whole system should work for no more $4,000.
And at that price, self-driving car technology could move from the realm of big-budget tech companies to the masses. He has funding from a Romanian company to begintesting a prototype this summer.
The advantages of self-driving cars are many, noted Budisteanu. More than 2 million people die each year in car wrecks. An additional 50 million people are injured in traffic accidents.
"And 87 percent of the car accidents are only because of human mistakes," he said. "They don't see the cars, they don't see the traffic signs … the self-driving car will see everything."
Budisteanu received the $75,000 Gordon E. Moore Award Friday at the Intel International Science and Engineering Fair in Phoenix, Ariz., which featured approximately 1,600 young scientists from around the world selected from 433 affiliate fairs in more than 70 countries, regions and territories.
In addition to Budisteanu, a $50,000 prize was awarded to Eesha Khare, 18, of Saratoga, Calif., for the development of a tiny supercapacitor, a type of energy storage device small enough to fit inside a cellphone that can fully charge in 20 to 30 seconds.
Henry Lin, 17, of Shreveport, La., was awarded a $50,000 prize for simulating thousands of galaxy clusters in a project that will allow astrophysicists to better understand dark matter, dark energy, and the balance of heating and cooling in the universe's most massive objects.
Prizes were also awarded for "best of" in each of the categories, which span fields from animal and environmental sciences to chemistry and computer science.
"All the Intel International Science and Engineering Fair finalists here this week show great promise in harnessing the power of science and innovation to solve problems and create opportunity for our global community," Elizabeth Marincola, president of the Society for Science & the Public, said in press release.

Teen's invention could charge your phone in 20 seconds


Waiting hours for a cellphone to charge may become a thing of the past, thanks to an 18-year-old high-school student's invention. She won a $50,000 prize Friday at an international science fair for creating an energy storage device that can be fully juiced in 20 to 30 seconds.

The fast-charging device is a so-called supercapacitor, a gizmo that can pack a lot of energy into a tiny space, charges quickly and holds its charge for a long time.
What's more, it can last for 10,000 charge-recharge cycles, compared with 1,000 cycles for conventional rechargeable batteries, according to Eesha Khare of Saratoga, Calif.
"My cellphone battery always dies," she told NBC News when asked what inspired her to work on the energy-storage technology. Supercapacitors also allowed her to focus on her interest in nanochemistry — "really working at the nanoscale to make significant advances in many different fields."
To date, she has used the supercapacitor to power a light-emitting diode, or LED. The invention's future is even brighter. She sees it fitting inside cellphones and the other portable electronic devices that are proliferating in today's world, freeing people and their gadgets for a longer time from reliance on electrical outlets.
"It is also flexible, so it can be used in rollup displays and clothing and fabric," Khare added. "It has a lot of different applications and advantages over batteries in that sense."
Khare's invention won her the Intel Foundation Young Scientist Award at the Intel International Science and Engineering Fair, conducted this week in Phoenix, Ariz. 

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