Tuesday, March 20, 2012


World's smallest transistor 'created'

Scientists have created what they claim is the world's smallest transistor, using a single phosphorus atom. An international team at the University of New South Wales, Purdue University and the University of Melbourne, has described the smallest transistor ever built in the 'Nature Nanotechnology' journal.
Michelle Simmons, who led the team, says the development is less about improving current technology than building future technology."This is a beautiful demonstration of controlling matter at the atomic scale to make a real device. Fifty years ago when the first
transistor was developed, no one could have predicted the role computers would play in our society today."As we transition to atomic-scale devices, we are now entering a new paradigm where quantum mechanics promises a similar technological disruption. It is the promise of this future technology that makes this present development so exciting," Simmons said.
A single phosphorus atom is just 0.1 nanometres across, which would significantly reduce the size of processors made using this technique, although it may be many years before single-atom processors actually are manufactured.However, the single-atom transistor does have one serious limitation -- it must be kept very cold, at least as cold as liquid nitrogen, or minus 196 Celsius.
"The atom sits in a well or channel and for it to operate as a transistor the electrons must stay in that channel. At higher temperatures, the electrons move more and go outside of the channel. For this atom to act like a metal you have to contain the electrons to the channel. "If someone develops a technique to contain the electrons, this technique could be used to build a computer that would work at room temperature. But this is a fundamental question for this technology," Gerhard Klimeck, a team member, said in a release by Purdue University.

Sunday, March 4, 2012


Difference between ONLINE and OFFLINE UPS

Offline UPS

Offline UPS supply grid power to electrical and electronic devices during normal power supply. It switches to battery power only during power failures and other power problems. As the grid power is bypassed to the load during normal power supply, it is known as Offline UPS. As the UPS is used only during power problems it is also known as Standby UPS. Offline UPS is also spelled as Off-Line UPS or Off Line UPS. Apart from bypassing power to the load, Offline UPS also charges the connected batteries during normal power supply. The bypassing of power results in exposing the load to electrical noises and surges. Therefore, they are not recommended for very sensitive and critical electronic devices. During power failures and other power problems, they switch from grid power to battery power fast enough to prevent computers from rebooting. The switchover time is usually between 2 to 20ms.


Online UPS - Online UPS supply power to electrical and electronic devices from batteries all the time. The UPS first converts grid power to charge the batteries and then discharges the batteries to power the load. As the battery power is supplied to the load at all times, it is known as Online UPS. The grid power is converted from (Alternating Current) AC to DC (Direct Current) to charge the battery and the battery power is converted from DC to AC to power the load. Therefore online UPS is also known as Double Conversion UPS.

As Online UPS always provides power from the battery, the load always gets clean power regardless of any power problems. Therefore, Online UPS is recommended for sensitive and critical electronic devices. Online UPS provide a layer of insulation or electric firewall. Any change in the input voltage or frequency does not affect the output voltage and frequency. Therefore, the load is shielded from all power problems.