Monday, October 18, 2010

3A Universal Power Supply

This universal power supply is universal in the true sense. With a output continually variable from 1.25 volts to 25 volts, this power supply is left with hardly any needs that it can't fulfill.The power supply is short circuit protected and  has in-built thermal overload protection.

As shown in figure, the power supply uses an LM350 type variable regulator. The IC in a TO-3 package and resembles the common 2N3055 and AD149 transistors. VR1 provides voltage control.R1,D2 and C2 are the accompanying components. The input voltage is obtained from an 30 volt source such as a transformer etc. The diode D1 provides a path for C3 to discharge  when the power is turned off. The output wires carry heavy currents, so adequate care must be taken to ensures the use of thick wires and terminal to prevent failures.A standard transistors type heat-sink must be used. 

Sunday, October 17, 2010

DC motor control a AVR ATmega8

DC motor control using the PWM counters of AVR ATmega8 microcontroller. I had used a DC motor from an old personal stereo cassette player. The circuit provides speed and direction control of the motor. The PWM waveforms are used for driving the MOSFET H-bridge as shown in the schematic:

At a time only one of the two PWM channel is active, driving only two MOSFETS (either Q1-Q4 or Q3-Q2). Other two MOSFETs remain OFF. Whenever the Direction Control switch is toggled, the PWM channel is also changed, driving the alternative pair of MOSFET, which changes the direction of current flow through motor, resulting in the direction change in rotation of motor shaft.

Wednesday, October 13, 2010

Iran Introduces Walking Humanoid Soorena Robot

Iranian President Mahmoud Ahmadinejad unveiled a new Asimo-like robot, which they intend to use in “sensitive jobs,” according to government newspapers. The report did not elaborate what the robot can do apart from dragging its feet across the floor.
Soorena-2, which was named after an ancient Persian warrior, measures 1.45 meters (4 feet 9 inches) in height and weighs 45 kilograms (almost 100 pounds). It was an updated creation by the robotics team at Tehran University after its predecessor was introduced two years ago.
Another news reports that the Soorena-2 will eventually get vision and speech modules. The robot is part of a number of scientific projects Iran has been researching, from cloning to stem cell research to satellite technology.

A new Iranian humanoid robot called Soorena-2 has been designed by developed by 20 researchers and engineers from the University of Tehran to be used to conduct what are being called "sensitive jobs". What these jobs actually are we don’t know. The President Mahmoud Ahmadinejad just recently showed off this 4.7-foot walking robot to the world. Soorena’s, who’s been named after an ancient Persian warrior, weighs in at 99 pounds and is capable of 12 foot movements, eight hand movement and the two for the head. We still don’t know exactly what Soorena-2 is capable of, or is just one of those technological advancements one likes to show off.


Saturday, October 9, 2010

BlackBerry VM-605 Specification

The BlackBerry VM-605 features a loud speaker for clear calls. Built-in FM transmission allows drivers to make use of their vehicle’s stereo for calls and music. The most interesting features in the VM-605 is that it was designed to work with GPS applications like TeleNav that announce your directions over the speakerphone. BlackBerry has included a button lock function. Holding the FM, Volume Up, and Front Panel buttons for four seconds will power off the unit and lock the keys, preventing accidental calls. Repeat the process to awaken the unit.

More Specifications Blackberry VM-605 :
* Music and calls through your car stereo speakers: Play calls and music from your cell phone on your car stereo via FM and Bluetooth transmission. FM Transmission with Auto Station Scanning for a surround sound effect.
* Multiple Languages: Easy to operate because the VM-605 gives spoken information in 9 languages. Blackberry VM-605 also speaks the CALLER ID so you control who to answer!
* Echo and Noise Cancellation: Background noise reduction and echo cancellation makes calls clear.
* GPS Application: VM-605 Speakerphone is designed to work with GPS applications like TeleNav that annouce your directions over the speakerphone or car stereo. * Compatible with select third-party GPS mapping applications. Check with your service provider for supported features and services.
* Battery: Talk continuously for up to 13 hours OR standby for up to 240 hours before you need to recharge the internal 1100mAh Lithim Polymer battery. Automatic Time-Out shutdown feature also saves battery life. Recharge from the included Micro USB auto charger or any other AC or DC Micro USB Charger.
* Lightweight and compact: Blackberry VM-605 weighs 86 grams (3.03 oz.), and measures only 123 mm x 57.6 mm x 16 mm (4.84 inches x 2.27 inches x 0.63 inches).
* Automatic reconnect: Auto-pairing for no-nonsense start up with your cell phone.
* Basic call handling: Features Answer/end calls, Reject calls, Voice-dialing through your cell phone, Last number redialing, and Mute.
* Bluetooth A2DP, HF and HSP profiles are all supported on this Bluetooth version 2.0, class 2 device for better connectivity up to 30 feet away
* Click here to determine if your cell phone model is Bluetooth enabled, AND which Bluetooth profiles it can support.
* RIM Blackberry factory original one year warranty applies.
* Price range:  $59.99 – $74.99

Saturday, October 2, 2010

RAM and ROM memories in Micoprosesor

Computer memory devices come in two basic types,RAM and ROM. these words are not as helpful as they could be.RAM standers for 'random access memory, a term which can in fact be applied to both types.ROM is 'read only memory'  which means that the computer system can obtain information stored in the memory('read' it) but can't store anything new in it('write' to it').RAM stores can boat be read from and written to,but both ROM and RAM have the random access facility.Put simply,this means that any data byte stored in the memory chip can be obtained as easily as the next, it doesn't matter whereabouts in the chip it is.

floppy disc systems offer the same facility A program stored anywhere on the disc can (to all intents and purpose) be just quickly accessed as any other.Compare this to information stored on magnetic tape.The first program on the tape is much easier to access than the last -  if you want to do it automatically- so that a tape memory is not regard as being random access.

Rom memory chips are programmed by the manufacture; they contain the computer operating system and standard routines (mini program) that may be used quite frequently;there may be a routine to clear the screen,for example.This information is stored permanently in the ROM chip and is not lost when power to the machine is switched  off. It is termed a 'non-volatile' memory.There is no possibility at all of making future changes to the contents of a ROM chip.The ROM, as with all semiconductor memory devices,is in matrix form and the connections within are permanent.

RAM chips are used for storing the user's program,you can write information the them and read it back again entirely at random according to your programming needs,but all the information's is lost when the computer system is switched off; this is therefore termed a 'volatile' memory system.

 A user would normally 'save' the contents of RAM (usually the program) on floppy or hard disc before turning the power off; such systems are called memory backing store. It is possible to write a program and have is stored  permanently in a ROM chip, but the process is quite complex and requires programmable ROM is used which is programmed during manufacture and would be too expensive to produce in small quantities.