Universal Serial Bus

USB stands for ‘Universal Serial Bus’ .It is the next step in creating a computer interface that really works universally. It boasts cross-platform compatibility for Macintosh, Linux/UNIX, and all versions of Windows since 98SE. The USB connector ports are available standard on virtually every computing machine manufactured in the past eight years.

Ø  USB was designed to standardize the connection of computer peripherals, such as keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters to personal computers, both to communicate and to supply electric power

Ø  USB are now used to connect devices such as mobile phones, music players, personal digital assistances etc. to the computer.

Ø  USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.

Ø  USB mass storage devices are now widely used for data transmission.

Ø  USB devices are used to interface electronic devices with computer.

Many versions of USB has been released, such as USB 1.0, USB 2.0, USB 3.0 , based on the transfer rate. USB 3.0 has the highest transfer rate (625 MB/s), about 10 times more faster than USB 2.0 (60 MB/s)

USB standard connectors are of two types, USB standard A & USB standard B, based on their shape.

The structure of  USB 1.x and 2.0. are shown. The pin 1 provides +5 V, pin 2 (data-) & pin 3 (data+) are data pins, pin 4 is ground. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. 

Are CFLs Safe

ARE CFLs SAFE???......

      Compact Fluorescent Lights (CFLs) along with more traditional fluorescent lamps are now being aggressively marketed as environmentally friendly due to their reduced electricity consumption. Indeed, widespread replacement of incandescent bulbs with CFLs will greatly reduce electricity demand. However, there are safety issues that we often forgets ………………….

Ø  Long exposure of the shorter-wave ultraviolet (UV) light that escapes from the CFL can cause health problems such as skin problems , damaging of tissues etc..

Ø  CFL ,used to work on dimmer switches(if it is not specifically made to work with dimmers),can dramatically reduces the life of the lamp and also places you at the risk of fire. Also most photocells, motion sensors and electric timers are not designed to work with a CFL.

Ø  Fluorescent lamps create several hazards if broken. Breaking the glass can cause shrapnel injuries, along with the release of mercury and other hazardous compounds.

Ø  The most commonly cited fluorescent lighting hazard is mercury. Fluorescent and CFL bulbs contain a small amount of mercury. CFLs average less than 4 milligrams of mercury.  Mercury vapor is extremely toxic. Even in liquid form, contact with mercury is considered life-threatening or a "severe" risk to health. Even very small doses of mercury can cause severe respiratory tract damage, brain damage, kidney damage, central nervous system damage, and many other serious medical conditions.

Ø  Flicker and glare from fluorescent lights can also cause headaches and discomfort. Ever since fluorescent lighting was introduced in workplaces, there have been complaints about headaches, eye strain and general eye discomfort. These complaints have been associated with the light flicker from fluorescent lights.  

  CFLs MUST BE RECYCLED…

Heinrich Hertz