Accelerometers

Have you ever wondered how iphone’s cool features works ? How new laptops can protect their hard disk when it falls down ? How we get crisp images from a cameras even if we shake the device ? The answer is accelerometer.

Accelerometer in essence is not a new technology. Its been on the desk of researchers and scientists well from 1990s, but only recently with the help of latest technologies small scale accelerometers were made so that it can be used in the devices above mentioned.

Accelerometers are a special kind of device called MEMS- Micro Electro Mechanical System. There are various types of accelerometers. A simple one is having a cantilever beam which is suspended and some complex sensing circuitry. It converts the acceleration (force) to displacement which is then measured. New technology accelerometers looks nothing but like an IC (Integrated Circuit). It consists of a bubble producing system. It heats the gas bubble and another system senses the location of the hot bubble as the accelerometer is accelerated or tilted.

The application and use of new technology accelerometers are endless. Lets begin with the much awaited gadget of 2007, iphone.

Apple Iphone uses accelerometer to sense the tilt of the phone, so that it can switch from portrait and landscape modes.

New phones from Nokia such as 5500 uses accelerometers for many things. A small tap on the phone can control the music in phone. Nokia N95 and 70 also uses accelerometers. N95’s accelerometer function can be accessed even by third party software, but in N70 they use it only for tilt sensing in camera mode.

Sony Ericsson use accelerometers in a wide range of phones. In their phones you just need to shake the phone to change tracks. There are J2ME games incorporating accelerometer functions.

Are you tired, there are lot more to come, read along if you are that brave.

The Wii was a headache for the big players like Sony (PS) and Microsoft (Xbox). The Wii remote incorporate accelerometer for measuring tilt and movement so that it can be complemented on the screen.

Famous shoe brands such as Nike uses it to determine speed, distance of the runner. They attach the accelerometer in their shoes which does the sensing part. The result is shown on some device such as watch, which are also produced by Nike.

Tiny new technology which helps iphone, digital cameras do wonders.

Leading laptops have a security feature that claims it uses new technology to protect the data at all cost, even if the laptop falls down. Wonder how ? Here also they use the accelerometer, which is obvious. So when the laptop falls down, the accelerometer picks the motion and the write current is turned off, so that the disk remains scratch free.

Cam coders and digital cameras use accelerometers for image stabilization and anti-blur capturing. They “snap” the CCD sensors in the cameras if they detect a movement.

Accelerometers are in automotive for quite long. Its with the help of this device that air bags work. Any quick reduction in speed, ie a negative acceleration, will trigger the air bags.

Variable Frequency Transformers

With Variable Frequency Transformer power transfer can be done smoothly without noise.

America cannot produce all the power it drinks. It has to get help from its neighboring countries like Mexico to satisfy her. So power transfer between two grids must take place.

Circuits employing semi conductor devices were used for this purpose. But there is a problem. The power flowing in grid is in the form of AC-alternating current. This AC cannot be controlled using semiconductors. For that purpose we convert the AC to DC-Direct Current. Using the circuits we can alter any parameters of the power such as amplitude, frequency, phase etc. After that, DC is converted back to AC, ie we synthesize AC. But this AC is not as good as natural AC. The problem is harmonic distortions. As we change DC to AC a spike appears at each pulse, which is a noise and is undesired, but hard to eliminate.

With the help of new technology, VFT-Variable Frequency Transformers can do this. Variable Frequency Transformers can convert this power to and from grids without converting the power into DC thus eliminating the harmonic distortions. Another advantage with VFT is that we can have infinite phase shifts between the two powers where as in conventional devices we could have only few predefined phase shifts.

Even though VFTs employs latest technology, someone looking at the Variable Frequency Transformer will recognize it as a hydro generator. In fact AEP-American Electric Power, who has currently installed a VFT between Mexico-US grid, buys it from the same manufacturers who makes standard hydro generators.

Although Variable Frequency Transformers looks like a hydro generator, it seems like VFT has hydrophobia . There is not a drop of water involved here, although it is a hydro generator. The rotor of the Variable Frequency Transformer, is a big three phase electro-magnet which is connected to one grid and the stator, another three phase winding,a stationary winding which is connected to the other grid. When power starts to flow, the phase difference between stator and rotor cause the motor to rotate. The rotor shaft is connected to another motor, called a control motor. We apply torque on the shaft and can rotate the motor in any direction and the direction of the motor determines the direction of power flow. The Variable Frequency Transformer is like a phase shifter having infinitesimally small steps. Wonderful technology isnt it ?