Tuesday, March 31, 2009

Bluetooth-an open wireless protocol

Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS232 data cables. It can connect several devices, overcoming problems of synchronization.

The art of connecting things is becoming more and more complex every day. In this article, we will look at a method of connecting devices, called Bluetooth, that can streamline the process. A Bluetooth connection is wireless and automatic, and it has a number of interesting features that can simplify our daily lives.

Monday, March 30, 2009

Tuesday, March 24, 2009


A podcast (not to be confused or equated with Apple Inc's iPod) usually consists of a combination of audio and/or video that is made available for download via syndication. It is this syndication aspect of the delivery that separates a podcast from a file available for download. The files are usually retrieved with software applications (generically known as podcatchers) such as Apple's iTunes so that subscribers can listen at their convenience on devices that have intermittent, slow, or are otherwise lacking Internet access. The podcatcher reads an [RSS] feed (whose entries point to specific podcasts, usually sorted by date) to identify and retrieve the podcast.

Like the term broadcast, podcast can refer either to the content itself or to the method by which the content is syndicated; the latter is also called podcasting. A podcaster is the person who creates the content.

A podcast is syndicated via an RSS feed. This feed enables distribution over the Internet by syndicated download. Though the same content may also be made available by direct download or streaming, a podcast is distinguished from most other digital media formats by its ability to be syndicated, subscribed to, and downloaded automatically when new content is added.

Wednesday, March 18, 2009

Apple iphone

Apple previewed the next generation operating system for its iPhone and iPod touch mobile devices. In addition to opening up lots of new functionality for developers, users will also be pleased with new additions and more polish.

The event started with an introduction from Apple's Marketing Manager for iPod and iPhone, Greg Joswiak. He detailed some very impressive numbers concerning the iPhone OS ecosystem. 17 million iPhones and some 13 million iPod touches have been sold in the last two years, for a total of over 30 million devices running iPhone OS. There are currently over 50,000 registered app developers, 60 percent of which have never developed for any mobile platform. The App Store currently has over 25,000 apps available, resulting in over 800 million downloads to date.

Next, Senior Vice President of iPhone Software Engineering Scott Forstall came on the stage to detail some of the features and the over 1,000 new APIs available to developers. Developers now have a sanctioned way to sell additional content directly from an app, such as additional levels for a game or e-books for a reader app. Like the App Store, Apple handles all the logistics and keeps a 30 percent cut. Free apps, however, cannot offer this functionality. "Free apps remain free," said Forstall.

Wednesday, March 11, 2009


The Nike+iPod Sports Kit is a device which measures and records the distance and pace of a walk or run. The Nike+iPod consists of a small accelerometer attached to or embedded in a shoe, which communicates with either the Nike+ Sport band or a receiver plugged into an iPod Nano or an iPod Touch 2nd Generation. If using the iPod, iTunes software can be used to view the walk or run history.

The sensor and iPod kit was revealed on May 23, 2006 but for a short time was unavailable for purchase. The kit is able to store information such as the elapsed time of the workout, the distance traveled, pace, or calories burned by the individual wearing the shoes, and display it on the screen or broadcast it through the headphones of an iPod.

The sensor and Sport band kit was announced in April 2008. The kit allows users to store run information without the iPod Nano. The Sport band consists of two parts; a rubber holding strap which is worn around the wrist, and the receiver which resembles a USB key-disk. The receiver displays information comparable to that of the iPod kit on the built-in display. After a run, the receiver can be plugged straight into a USB port and the software will upload the run information automatically to the Nike+ website.

As of August 2008 Nike+ iPod Gym launched- now users can record their workouts on Gym equipment including Life Fitness Treadmills, Cross-Trainers and Upright and Recumbent bikes. Users don't need a Sports Kit for this, they simply plug their iPod Nano into the iPod connector on the cardio equipment in their gym. Nike+ lets a user track this data as cardio miles on the web site.

Wednesday, March 04, 2009

Solder-joins metallic surfaces

A solder is a fusible metal alloy with a melting point or melting range of 90 to 450 °C (200 to 840 °F), used in a process called soldering where it is melted to join metallic surfaces. It is especially useful in electronics and plumbing. Alloys that melt between 180 and 190 °C are the most commonly used.

The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning '‘to make solid’'. Solder can contain lead and or flux but in many applications solder is now lead free.

Tin/lead solders are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder’s tensile and shear strengths. At the retail level, the two most common alloys are 60/40 Sn/Pb and 63/37 Sn/Pb used principally in electrical work. The 63/37 ratio is notable in that it is a eutectic mixture, which means:

1. It has the lowest melting point (183 °C or 361.4 °F) of all the tin/lead alloys; and
2. The melting point is truly a point — not a range

At a eutectic composition, the liquid solder solidifies as a eutectic, which consists of fine grains of nearly pure lead and nearly pure tin phases, but in no way is it an intermetallic, since there are no tin/lead intermetallics, as can be seen from a tin/lead equilibrium diagram.