Monday, January 4, 2016

Which LED Bulb is Good? (LED light bulbs buying guide)

LED is the latest trend in the lighting industry. Looking at the way things are moving, LEDs surely look to revolutionize the lighting market in future. Small bulbs that were used as power indicators for appliances, look to light up the whole living space now. Technology improvements have made LEDs useful for home and office and have also made them much affordable now (still expensive as compare to CFLs or incandescent bulbs). Several manufacturers have come out with luminaires that use LED for lighting. These luminaires are available for all purposes: spot lighting, indoor lighting, outdoor lighting, street lighting, floodlights, garden lighting, general purpose lighting, etc. With this guide we would like to provide you information that can help you choose the right kind of LED light for your purpose.

What is LED and how it differs from other types of lights?

LEDs are a member of type of lighting most commonly referred as solid-state lighting.  This type of lights illuminate when current passes through a semi conductor material. They produce more “light” and very less “heat”. In comparison an incandescent bulb lights up when the filament in it heats up. Thus it releases 90% of its electricity as heat. CFLs or tubelights light up when electricity current is passed through tube containing gases. CFLs also release heat but less than incandescent and more than LEDs.
The other major difference is that LEDs are unidirectional (or emit light in a specific direction) but incandescent and CFLs emit light in all directions.

What are the different parts of LED bulb?

Typical LED bulbs contain one or multiple LED chips mounted on a circuit board that is programmed to control the LED lighting. The whole thing is mounted on a heat sink to manage the heat generated from LED.

What are the benefits of using LEDs?

  1. The biggest benefit of using LEDs is their life. They have a life of 25000-50000 hours of usage. So if it is used for 4-5 hours a day, it can run for 15-25 years without needing a change.
  2. Good quality LED bulbs are maintenance free. So they are like put it and forget it.
  3. They can give better output (brightness) or lumens per watt if beam angles are lower (more on beam angles in the details below).
  4. The light output of LEDs remains constant through its life only decreasing towards the end of their life.
  5. They do not flicker even when dimmed.
  6. Lot of them come with good warranty (of up to 10 years) which means you investment now will last for up to 10 years!
  7. They are eco-friendly. They do not use mercury (used in CFLs), which is harmful for environment.

What are the drawbacks of LEDs?

  1. LEDs are unidirectional or emit light in a specific direction. So they cannot light up the whole area (of a room) unless diffusers and reflectors are used. Thus they are excellent for spot lighting but not as great for general-purpose lighting.
  2. Although LED chips have a long life but the life of LED bulbs depend on how well the heat sink and the circuit is designed. A poorly made LED bulb may not last longer than a year (if right heat sink and capacitors are not used. In many countries LED bulbs are rated based on their performance. In India it is better to buy LED of a good brand or buy one that comes with a longer warranty.

What are LED beam angles and how to use them?

As we said, LEDs are unidirectional or emit light in a specific direction, it is important to figure out the right spread of a LED light in degrees before using it. This spread is mentioned on LEDs as beam angle. Typical beam angles that are available in the market are 15, 30, 45, 60 and 100 (with some very few with 120 and 180 as well).
Beam angles less than 30 are excellent for spotlights. Their output (brightness) or lumens per watt is highest available in the market. Most of them have wattage of less than 5 and are of great use in Shops (where focused lighting is needed on products), Workshops where a specific work is to be done or at homes where specific area has to be focused with decorative lighting. One or more such lights can be used near walls as spotlights.
Beam angles greater than 30 are suited for high power LED lamps usually used for downlighting. They can be put on ceiling to illuminate an area in a room. They typically are of more than 5W rating and multiple such downlights are to be used to illuminate a room.
A 30-45 degree beam angle is good if the ceiling is high (more than 10-11 ft). If the ceiling is less than that, then it is better to use 60-100 degree beam angle. Based on requirement, multiple such downlighters have to be used and kept 3-4 mts apart from each other to get appropriate lighting.
Lower beam angles are also good for outdoor lighting and street lighting purposes where they can be excellent replacement for halogens that consume a lot more electricity as compared to LEDs. Housing societies can benefit by using LED street lights.
The increased beam angles are achieved by putting reflectors and diffusors, and the biggest drawback for this is that the lumens (or brightness) decrease as beam angles increase. So a LED bulb with higher beam angle may give same brightness as a CFL for the same wattage.

How do some LED bulbs available in market have more than 120 beam angle?

Lot of LED bulbs available in the market have diffusors to disperse the light at greater angles. This makes sure that the light spreads across the room. But their brightness will be equivalent to a CFL bulb of same wattage. These are generally designed as replacement for CFLs and incandescent bulbs.  The benefit of these bulbs is that they are long lasting and ecofriendly.

What other factors should be considered while buying?

As we discussed in our article on task based lighting, color temperature of the bulb should be considered based on the mood to be set in the room. LED bulbs are available in various color temperatures: Cool Daylight (White) to Warm White (yellow). Choosing the right one based on the mood to be set in the room is important.
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Sunday, December 27, 2015

13 Reasons Why Your Computer is Slow

Computers slow down for any number of reasons, but most of those boil down to one thing – us using them. As you download programs, install extensions, surf the web, create files and fill your hard drive with movies and music, inevitably you'll build up virtual detritus that will impact your PC’s performance. Happily, much of that impact can be mitigated with better electronic hygiene habits.
We had a chat with Bineesh Chengalayi, Admin of ComputerKerala about the most common reasons your computer is slowing down – and the simple measures you can take to get its groove back.

1. Your browser has too many add-ons

Not all browser extensions are created for good. “People often assume a slow computer is because of a virus, but a lot of time it'll be a browser add-on or plugin bundled with a free software download,” Bineesh says. These add-ons may proclaim themselves popup blockers or search protectors, but they're actually browser adware that can slow your computer down by downloading ads and popping up ads every time you open your browser.

Fix it

Disable or remove browser extensions and toolbars you don't really need:
Firefox: Hit the menu button on the far right, select Add-ons / Extensions, then select disable or remove for each item on the list.
Chrome: Right-click on any extension button / Manage Extensions, then uncheck the box to disable a particular item, or click the trash can to wave it goodbye.
Safari: Hit Safari (top left) / Preferences / Security / Extensions, then select an item to uninstall. You can also turn off all Extensions here.
Internet Explorer: Tools / Manage add-ons / Show All add-ons, then select the offender(s), and click disable or remove.

2. Your hard drive is failing

“Hard drives have moving parts, so they all fail eventually,” Bineesh says. “There's no way to guard against it except backing up your files.” As for solid state drives (SSDs), which don't have moving parts and are theoretically less likely to break down, “that's kind of a myth,” Bineesh says. While they may not suffer mechanical breakdown, their data can still be corrupted. “When they do fail, it's much more difficult to recover the data,” Bineesh says.

Fix it

Run a hard drive check, says Bineesh. He recommends installing a program called HDTune that runs a health check on your hard drive to diagnose it healthy or ailing. Avoid dropping, throwing or otherwise causing impact to the hard drive to extend its lifespan.

3. You're running too many programs at once

Doing a trillion things at once is exactly why we have computers but, at some point, your little bundle of artificial intelligence is going to falter. Your computer's ability to run multiple programs at the same time hinges in part on its RAM (random access memory), which allows it to switch from processing one program to another with seeming fluidity, but if the demands of the open programs are outstripping your computer's memory and processing power, you'll notice a slowdown.
“Lots of folk have to keep in mind not to have too many windows open,” Bineesh says. That includes minimized windows, which continue to run in the background, sucking up processing power.

Fix it

Shut 'em down. In Windows 8, programs are built so that they run in the background for a while, thenautomatically shut down. But if you want to manually shut one down and ensure all associated files shut down with it, drag from the top of the screen to the bottom, and hold there until the icon flips over.

4. Too many browser tabs are open

If you're in the dozens of open tabs camp (“All the better to never lose a link”, you claim), your browser is likely hogging far more than its fair share of RAM.
“Having multiple browsers open can slow down the works, just like if you had 20-plus tabs open,” Bineesh says. Extra slow points if any tabs are also auto-refreshing (say, a live blog).
What's more, having a glut of browser tabs full of supposedly crucial information doesn't exactly help our efficiency or mindfuless

Fix it

Bookmark those “necessary” links (for organization's sake, in a Bookmarks folder titled “To Read”) and shut those tabs down. Even better, One-Tab for Chrome and Firefox does the work for you, compiling all your open tabs into a simple list on a single tab, which can then be accessed as needed.

5. Rogue programs are hogging all the processing power

It's not always a heavy-duty video or music app that's eating up your computer's processing power.
Some programs or system processes may be stuck in a loop or have encountered an error.

Fix it

Check how much processing power programs and processes are using by heading into Task Manager (Windows; Ctrl+Alt+Delete) or Activity Monitor (Mac; in Applications / Utilities). For both, click the “CPU” tab to order the programs by how much processing power they're taking up. If a program that you're not actively using is still up there in the top few programs, you can select to quit the process.
And, when it comes to browsers, Internet Explorer is especially heavy on your computer, Bineesh says. “You don't have to run it but don't remove it [if you got it bundled with your Windows PC] – it could cause problems as it's very tied to the operating system,” he says. Instead, he suggests the lighter, more secure Chrome.

6. You have an overzealous antivirus program

Having an active anti-malware program is a vital part of computer hygiene – but yours may be running regular background scans at the worst possible times. “Virus scans slow down the works because they're running in the background,” Bineesh says. Some antivirus programs may be set to weekly full scans, which can take a few hours and suck up a lot of processing power.

Fix it

Head into your antivirus settings and configure it to scan late at night when you aren't using the computer, says Bineesh. (However, that feature may not be available on some free antivirus programs – which makes a good case for upgrading.)

7. You have a virus

If it's not the antivirus, it could be the virus. Viruses, spyware and other malware can slow down your computer as they mess around with everything from hijacking your browser to pushing advertising or phishing sites, to crashing your computer.

Fix it

Run a malware scan. “The best free one we like is Avast,” Bineesh says. For more free and paid options, check out our Techlicious top picks for security software programs for Windows PCs and Macs. 

8. You have too many startup programs

Newly downloaded programs often try to weasel their way into your Startup menu (Windows) or Login Items (Mac). If you didn't uncheck the box for that permission, you could have dozens of unnecessary programs vying to be ready and running as soon as your computer boots up (as if that's happening any time soon).
“Having too many icons on the desktop can also slow down a Mac's startup,” Bineesh says.
While some programs – such as antivirus and firewall software - should be allowed to run from startup, others – such as iTunes or Microsoft Office – could quite easily stay closed until you actually need to access a file from their digital depths.

Fix it

Mac: Applications / Systems Preferences / User Groups / Login Items, then uncheck unneeded programs. Delete desktop icons you don't use by trashing them or, in the case of files you've saved to desktop for convenience, reorganizing to the appropriate folder.
Windows 8: Right-click on the task bar / Task Manager / Startup tab, then right-click on the programs you want to remove and select Disable.
Windows 7 and older: Start button, then search for System Configuration. Go to Startup tab, then uncheck each of the programs if you don't want starting when the system boots up.

9. Your hard drive is 90% full 

When your hard drive gets to 90-95 percent full, that's when you see things moving at a crawl, Bineesh says. “A full hard drive can also prevent a computer from starting up. It's best to optimize your space as much as possible – move stuff to the cloud, or delete the stuff you're not using,” he says.”
Hard drive space is taken up by programs, updates to programs, and downloads, as well as temporary files and associated files of deleted programs, so you may be able to clear a good amount of space just by emptying your trash. Check your hard drive situation by (Mac) clicking the apple and selecting About this Mac, or (Windows) hitting Start / Computer and right clicking the primary hard drive (usually C:), then go to Properties.

Fix it

Deep clean your computer of unnecessary files from unused programs to defunct downloads and temporary files.
“It's good to remove bloatware – Toshiba, Lenovo and other PC manufacturers put their own software on computers that are supposed to run utilities or cleanup,” Bineesh says. And in terms of that ancient computer cleaning ritual defragging, “that really only works on Windows XP computers and older,” says Bineesh. System backups and restore points also can take up a huge amount of space, so don’t keep more backup versions than you really need.

10. Your OS is way too slick

It's the age old battle of appearance over performance: Having visual effects enabled – aka eye candy like those snazzy transitions for minimizing windows – can impact the speed of your PC (and to a lesser extent, Mac), if its hardware only just skates within the minimum requirements for your OS of choice.
“If you have a good video card – that's 1GB of RAM on the video card or better – you're OK,” says Bineesh. “But less than that, [having visual effects enabled] can slow your computer down.”

Fix it

Windows 7 and older: Start / Control Panel / Performance Information and Tools / Adjust Visual effects, then click adjust for best performance or manually choose which effects you'd like to keep.
Windows 8: Windows key + X / System / Advanced System Settings / Performance Settings / then select as above.
Mac: System Preferences / Dock, then for minimizing applications, change that super-swish Genie effect to a utilitarian Scale effect (basically just disappearing). Uncheck “Animate Opening Applications”.

11. Your room is too dusty

Sometimes the problem is not internal but external – is the back of your CPU casing matted over with dust? This can prevent ventilation which cools the processors as they whir away in an attempt to run Photoshop, Spotify, Outlook and Skype. And nobody wants a hot computer – heat increases the likelihood of malfunctions and crashes.
As for laptops, any time you notice your laptop heating up, you should check that its vents, usually on the sides, aren't blocked. For example, don't put your laptop on something soft like a pillow where it can sink in.

Fix it

Dust off the ol', um, dust. If it's really severe, you can use a vacuum cleaner (carefully) or a canister of compressed air.

12. You don't have enough memory

If you've deep-cleaned your computer and modified your browser tab habit, but your computer is still slow (and you own a PC), you might want to consider a minor upgrade in the form of additional RAM.
Some programs take a lot of your computer's RAM to run – for example, programs that work with huge files such as photo or video editing software. “A lot of people try to run Photoshop or some graphics-heavy program on a entry- or mid-level computer that can't handle it,” Bineesh says.

Fix it

Bineesh recommends a minimum of 2GB of RAM, or 4GB if you do graphics-heavy work on your computer. Fortunately, upgrading the RAM on your PC is inexpensive and a task most people can handle themselves. 

13. You need to restart your computer

The reason restarting seems to solve so many tech issues is that programs can get hung for a myriad of reasons. “A lot of stuff gets gummed up in the background. For example, if you turn off Outlook, background processes are still running,” Bineesh says. “You could 'end task', but a lot of folks are not that savvy about which one to end.”
Instead of manually digging into Task Manager (Windows) or Activity Monitor (Mac) to divine the root(s) of the sluggishness, restarting flushes out the system, a panacea for those rogue, resource-hogging programs and a clean slate free of files and fragments.

Fix it

Bite the bullet and shut things down. You even get the added benefit of having critical system updates applied that can only happen during a reboot.

Friday, December 18, 2015

Raspberry Pi

Raspberry Pi
The year was 2012, and while most eyes were looking at the imminent arrival of Windows 8, another computing story was quietly gathering momentum. Fast forward to today and it's amazing to think how far the Raspberry Pi has come since its launch.
This barebones PC launched for a pittance, and has astonishingly managed to become even cheaper, with the latest iteration - the Raspberry Pi Zero - costing just £4 ($5 over in the US, which is around AU$7).
It was designed to encourage kids to code, but despite its small size, this board quickly proved itself capable of so much more, able to handle everyday tasks like spreadsheets and word processing.
If the BBC Micro ushered in the first golden age of home computing, the Raspberry Pi has restored some of the faded glory to Britain's role as pioneers in this field.
Pi origin
The Raspberry Pi is the work of the Raspberry Pi Foundation, a charitable organisation founded in 2009. It's supported by the University of Cambridge Computer Laboratory and tech firm Broadcom, the latter of which makes the system-on-a-chip that powers the device.
Speaking to our sister magazine Edge on the eve of its launch, legendary games developer and Raspberry Pi Foundation head David Braben explained the Foundation's mission: "[In Raspberry Pi] you've got quite a powerful, very cheap device that anyone can carry around, take to school, and hopefully do interesting things with that make it seem less like it's purely a school thing."
Image: Liz Upton / Wikimedia
Raspberry Pi 2
In today's schools, IT education means IT literacy, not computer science - that is, teaching kids how to use applications rather than how to make them. According to The Royal Society, "we appear to have succeeded in making many people comfortable with using the technology that we find around us, but this seems to have been at the expense of failing to provide a deeper understanding of the rigorous academic subject of computer science." One of the Pi's aims is to help promote that understanding.
What's also apparent is that the Pi has also reawakened the same level of curiosity in adults too - and not just those eager to rekindle their dormant love of programming. The Pi's low cost and minimal power demands have proved it capable of filling in lots of gaps in the home, too. However, despite this niche appeal, the Raspberry Pi Foundation still firmly targets its use at the education sector.
Raspberry Pi box
There are currently four versions of the Raspberry Pi hardware. The cheapest model is the recently launched Pi Zero, which can be had for just £4 (or £8 with essential add-on kit). The two original models have been refreshed, and cost around £16 and £22 for the Model A+ and Model B+ respectively (that's around $24 and $33, or AU$33 and AU$45). The top of the line model is the Raspberry Pi 2 Model B, which can be had for £30 (around $45, or AU$63).
Note that this outlay buys you the basic board only - you'll need to provide your own power supply, cables, keyboard and display.
Pi diagram
Both the Model A+ and Model B+ use a single-core 700MHz Broadcom processor with a Videocore 4 GPU. That provides OpenGL ES 2.0, hardware-accelerated OpenVG and 1080p HD video. A microSD slot is provided for storage, and power is supplied via a MicroUSB connector. Both have grown their GPIO header to 40 pins, but retain the same pinout for the first 26 pins as the previous models to ensure backwards compatibility.
The Model A+ ships with 256MB of on-board RAM and sockets for HDMI, USB 2.0, RCA video and 3.5mm audio jacks.
The Model B+ increases the RAM to 512MB and ups the number of USB ports to four. It also added a 10/100 Base-T Ethernet connection. There's no Wi-Fi in either version, but you can easily hook up a USB Wi-Fi adapter.
The Raspberry Pi 2 Model B utilises a 900MHz quad-core ARM Cortex-A7 CPU with VideoCore IV 3D graphics core. There's 1GB RAM on board too, but in all other respects it's identical to the Model B+ in terms of board layout and connectivity.
The newest model, the Pi Zero, is half the size of the Model A+, yet utilises a 1GHz single-core Broadcom SoC, backed up with 512MB RAM. Connectivity is limited to two MicroUSB connectors (one for power) and one mini-HDMI port, plus the obligatory microSD slot for storage. There's a HAT-compatible 40-pin header (pins are provided as part of the Pi Zero Kit, which also includes full-size adapters for the mini-USB and HDMI ports). No Ethernet port is provided, although you can of course plug in a USB network adapter.
Image: Efa2/Wikimedia Commons
The Raspberry Pi software is Linux - Raspbian, to be precise - and it supports programming languages including Python, BBC Basic, C and Perl. You don't have to run this flavour if you don't want to - you'll find lots of alternatives that focus on specific objectives .
Note, however, that the architecture for the Model A+, Model B+ and Pi Zero is based around version 6 of the ARM architecture, which may not be supported by some more recent distributions, and that will limit your available options.
There's no such problem for the Pi 2 - its Broadcom BCM2836 processor is based on version 7 of ARM, allowing it to run the full range of ARM/GNU Linux distributions as well as Windows 10 IoT Core, a special version of Windows for low-powered devices.
Pi Zero
The original Raspberry Pi was launched in February 2012, while the Raspberry Pi 2 first emerged in February 2015. The Pi Zero's (pictured above) official launch was November 2015. In all cases, the original stock sold out in a heartbeat.
Despite the Pi's educational focus, each model has tended to enjoy a soft launch, with Raspberry Pi devices being bought by interested individuals rather than bought in bulk for schools.
The Raspberry Pi is officially available from two outlets - Element 14 and RS Components. Newer models are also available from SWAG, the official Raspberry Pi Store.
Raspberry Pi
David Braben said in 2012: "At the moment, on a normal machine you've got to know quite a lot to be able to boot Linux, fire up a compiler and get anything to compile. Just to say your own name on the screen is a challenge. Whereas on the BBC, you'd see in every shop that someone had typed, 'So-and-so is clever,' or 'So-and-so smells'.
Line 20, Goto 10: that almost entered the vocabulary, it's so straightforward. It's understandable even to someone who hasn't done programming. It would be great if you could take that and wrap it in something where it's easy to create something - websites, for instance - very easily."
The launch of Raspbian - the official Linux distro for the Raspberry Pi - has attempted to rectify this problem, with the current build now booting to a user-friendly point-and-click desktop environment rather than the traditional command line by default.
There's also potential for the Raspberry Pi to play a role in developing countries - its simplicity means it's much sturdier than a laptop, and as we've already seen it's exceptionally cheap, particularly with the new Raspberry Pi Zero model

Know your Internet browser shortcuts

Know your Internet browser shortcuts

There are dozens of different shortcut keys that can be used with Internet browsers. Below are a few of our top suggested Internet browser shortcuts.
  • Press Alt + D or Ctrl + L to move the cursor into the address bar.
  • Hold down the Ctrl key and press the + or -to increase and decrease the size of text. Ctrl + 0 will reset the text.
  • Press the backspace key or press Alt key + left arrow to go back a page.
  • Press F5 or Ctrl + R to refresh or reload a web page.
  • Press F11 to make the Internet browser screen full screen. Press F11 again to return to the normal view.
  • Press Ctrl + B to open your Internet bookmarks.
  • Press Ctrl + F to open the find box to search for text within the web page you are reading.

Sunday, May 25, 2014

Most frequent Errors for the Internet user

This are Very Comman and most frequent Errors for the Internet users here are the Error Codes and the Reasons for their arrival.This codes should know by ever internet user

- Error 200 – OK
It means the Action is Completed Successfully.
- Error 204 – No Content
The Server has received a request,But there is not Information available to send it Back.
- Error 400 – Bad request.
The Request was impossible to be satisfied.
- Error 401 – unauthorized request.
It mean that the user has failed to provide a vaild Password or Username to the directory.
- Error 402 – Payment Details Required.
-Error 403 – forbidden.
It implies to when  Request does not specify a Directory name or the File name.
- Error 404 – Not found.
This is Very Comman Error it mean that the file you are Requested is Not Found.
- Error 500 -Internal error.
It implies that Server has encountered an Unexpected Condition.

- Error 501 – Not Implemented
The server does not support the Facility or Function that is Required.

- Error 502 – Bad Gateway
It mean that the Server Cannot Request Command activity due to High-load.

- Error 503 -Service unavailable.
This is Due to Overload in Server and it is Temporary Issue.

- Error 504 – Gateway Time-Out
The Sever did’t Respond but the Gateway is Waiting for it.

- Error 505 – HTTP Version not supported/ DNS Lookup 
This are the most Comman Internet Errors and their Reasons.