BSNL Tablets

Indian Telecom company BSNL launches three tablets designed by Pantel Technologies which are going to provide healthy competition to datawind’s Aakash and Ubislate 7+. These tablets have better configuration than Aakash and Ubislate 7+ and are in three different price ranges.

These three tablets are

Penta TPAD IS701R

Penta TPAD WS704C

Penta TPAD WS804C

The cheapest of them is Penta TPAD IS701R which has price of 3250 Rupees and it will give tough competition to Aakash and Ubislate 7+.

Penta TPAD IS701R

Price: 3,250 Rupees.

Penta TPAD IS701R doesn’t has SIM card slot but it can be connected to internet via 2G or 3G USB modem. It has Wi-fi connectivity and Android 2.3 (Ginger Bread) operating system.

Talking about its internal configuration, it has 1GHz (ARM11 IMAP210) Processor along with 256 MB DDR2 RAM which is faster than Aakash and Ubislate 7+.

It has 7 inch resistive touch screen which has 800 x 6oo resolution.

It has HDMI port via which it can be connected to an HDTV. It has a gravity sensor (G Sensor) which enables applications like motion gaming and etc.

It has battery of rating 3000mAH.

Internal memory of 2 GB which can be extended upto 32 GB.

It also has a 0.3MP (Digital or VGA) front facing camera.

Image of Penta TPAD IS701R is shown below

Penta TPAD WS704C

Price: 10,999 Rupees.

Penta TPAD WS704C has sim card slot and Android 2.3 (Ginger Bread) operating system.

It has 1GHz (ARM11 IMAP210) Processor along with 512 MB DDR3 RAM which provides good multitasking.

It has 7 inch capacitive touch screen which has resolution of 800 x 600. It is multi touch enabled.

It has a USB and a HDMI port.

It has battery rating of 4000mAH.

It has Internal memory of 4 GB which can be expanded later.

It has 3.5 mm audio jack and 0.3 MP front camera along with 2 MP rear camera.

It has other stuffs like Wi-Fi, Bluetooth, GPS and G-sensor.

Image of Penta TPAD WS704C is shown below

Penta TPAD WS804C

Price: 13,500 Rupees.

Penta TPAD WS804C has sim card slot.

It has ARMv7 1.2GHz processor based on Cortex-A8 architecture which is better than the previous one. It has 512 MB DDR3 ram.

It has 8 inch capacitive touch screen which has resolution of 800 x 600.

It has a USB and a HDMI port.

It has Internal memory of 4 GB which can be expanded later.

It has 2MP camera at the back of it along with 0.3 MP front camera.

It also has stuffs like 3.5mm audio jack, Wi-Fi, Bluetooth, GPS and G sensor.

Image of Penta TPAD WS804C is shown below.

Comparison Of BSNL Tablets 

Solar Paint

Energy crisis is a big issue in today’s era. Scientists are trying to find more and more alternate sources of energy. One of them is solar energy. Solar energy is most common and ubiquitous energy source. We get enough energy in 1 hour from sun to fulfill our energy need for one year!!

Currently, people are using solar panels to generate electricity from sunlight. But cost for installation of solar panel is high and its efficiency is near to 10% to 15%.

Researchers at the university of Notre Dame in US has developed a paint which can generate electricity from light when it is spreaded on a conductive surface. Indian origin professor Prashant Kamat is leader of this team. These researchers have called this paint as ‘Sun-believable Solar Paint’.

Power producing nano-sized particle made of titanium dioxide is used in this paint. These nano particles are called quantum dots. The paint is based on nano sized particles of titanium dioxide (quantum dots) coated with cadmium sulfide or cadmium selenide. These particles were mixed with water and alcohol to create a smooth paste.

“When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity”: Prashant Kamat.

This paint doesn’t need any special equipment to apply on the surface it simply need a conventional paint brush.

This paint has light to energy conversion efficiency of 1% which is low compared to solar panels. But production cost of this paint is very low which makes it worth.

Researchers believe that small improvement in efficiency can make it commercially successful.

How does Cell Phone Jammer Work?

More and more number of people is using cell phones now a day. The number of cell phone users in the world is increasing rapidly. People feel connected by having cell phone with them and they feel being cut off with the world without cell phone. Cell phones are being almost ubiquitous. Because of this ubiquitousness of cell phones, they are causing many problems in society. Some people don’t know when to talk, when to put mobile on silent mode or when to switch off mobile. These people cause disturbance in society. You would hate those people, who are spoiling your movie by talking loudly on cell phones in theatre. Some people talk in hospitals and some in church and temple. To avoid these kinds of disturbances, cellular jammers are used at these places.

You would be surprised to know that cell phone jammers were used in Indian parliament to avoid disturbances caused by ‘ring tone’ of members and to prevent leakage of fresh information caused by journalists during the session. Journalists used to send SMS about the discussions in the parliament. To avoid this, cell phone jammers were used in Indian Parliament.

After knowing these facts one would wonder, what is a cell phone jammer and how does it work?

What is cell phone jammer?

Technically speaking, a cell phone jammer is a device used to block cell phones from receiving signals from base stations.

How does Cell phone jammer work?

To know the working of cell phone jammer you should know how does cell phone work? Briefly speaking, a cell phone works by sending and receiving signals to the mobile tower and from the mobile tower. These signals contain information. The cell phone jammer works on the concept of blocking cell phone to communicate with tower. Thus jammer prevents cell phones from receiving or establishing any call.

Cell phone jammers transmit the signals on the same frequency which mobile phones use. This way jammers create disturbance for mobile phones. Mobile phone is a full duplex device that means it uses different frequencies for listening and talking. Jammers block any one of these frequency by transmitting relatively high power signals (noise) on the same frequency. Because of this high power, a cell phone can’t identify the signal from tower and it keeps searching for signals. So one can see ‘no signal’ or ‘Searching for networks’ or ‘no service’ in mobile phone’s display.

There are two signals, one is cell phone to tower and another is tower to cell phone. Jammers generally try to disturb tower to cell phone signals because towers are placed at distance so signals coming from them has low power. So it is easy for jammers to disturb tower to cell phone signal.

Cell phone jammers generally consist of power supply, internal circuitry and antennas.

Basic block diagram of it is shown below

Power supply

There are mainly two types of power supply. One is battery and other is direct mains power. Small range jammers use batteries. These batteries look like a cell phone battery. While wide range jammers are generally fed up by mains power. But a disadvantage of it is jammer work till the electricity is present.

Internal Circuitry

The most basic circuits are used in jammers. One part of its circuit is a voltage controlled oscillator. Voltage controlled oscillator is a circuit which generates a signal of desired frequency. Another part along with it is a tuning circuit which allows to change the frequency. After that a random noise is inserted into the signal so that mobile phone can’t identify the signal. Next stage is amplifier which increases power of the signal. And last stage is antenna.

Antenna

Antenna is a device which transmits the signal. Generally there can be three or more than three antennas in a jammer. Each one is for specific use like GSM, 3G, DCS, Wi-Fi etc.

Here are some images of jammers

Cell phone jammers are available in a few meters to several kilometers range depending upon its application.

There some countries where the use of cell phone jammer is allowed (legal). And in other countries it is not allowed (illegal) or one must have a license to use it.

Memristor

Memristor is a combined word of Memory and Resistor. It is given name memristor because of its remembering property. Memristor can remember the amount of current passed through it!

Memristor is a two terminal passive circuit element which has non linear properties. When current through the device is in one direction, the resistance increases and when current through the device is in opposite direction, the resistance decreases.

But the main property which makes this component very special is when current passing through it stops, it retains the last resistance that it had, and when the flow of current starts again, the resistance of the circuit will be what it was when it was last active. That means it can remember the amount of current flowed through it. This property gives this component ability to work as memory device or data storage device.

Memristor was first theoretically invented in 1971 by Leon Ong Chua. He is a professor at university of California, Berkeley. Leon Ong Chua is widely known as father of nonlinear circuit theory and cellular neural networks. Leon Chua theoretically proved the existence of Memristor in a paper published by him in 1971. But unfortunately he could not find physical model of it.

But 37 years later, a team of researchers at Hewlett Packard (HP Labs) led by R Stanley Williams was able to make physical model of memristor in 2008. This model of memristor was developed by using a thin film of titanium dioxide and they are planning to launch it commercially as a memory device in the time frame of 2013 – 2014. The researchers also announced that memristor can be the replacement of flash memory, SSD, DRAM and SRAM.

Memristor is considered as fourth basic element of electronics. Resistor, Capacitor and Inductor are first three basic elements of electronic circuits.

This image is of a circuit with 17 memristors which is captured by an atomic force microscope.

RAM is a volatile memory that means the data stored in it disappears when the power is turned off. While memristor is a non-volatile memory, which means the data stored in it remains in it when power is turned off. It has a very fast read and write time so it can be used as a non-volatile RAM. Advantage of using memristor as RAM is computers don’t need to reboot every time when it is turned on.

”You could leave all your Word files and spreadsheets open, turn off your computer, and go get a cup of coffee or go on vacation for two weeks,” says Williams. ”When you come back, you turn on your computer and everything is instantly on the screen exactly the way you left it.”

Memristor has ability to remember wide range of electrical states unlike only “on” and “off” in digital components. Memristor can remember values in analog way. This ability makes memristors able to perform more complex tasks than todays computers.

Memristors will be cheaper and far faster than flash memory, and allow far greater memory densities. Read time of memristor is less than 10 nanoseconds and wrier/erase time is about 0.1 nanoseconds which is faster than flash memory.

Conventional memory storage device use flip-flops which can store only one bit but memristor is able to store four bits which can increase storage capacity. Memristors are energy efficient than RAM because memristor doesn’t require any energy to maintain the data srorage.

Memristor chips can be made using three – dimensional layered structure which can process and store data. Making process of memristor is easy and completely compatible with today’s CMOS chip making process. It can be scaled to very small geometries without losing its properties.

Memristors can also be used as a microprocessor.

Researchers believe that the computers made using memristor can process and associate information in a manner similar to that of the human brain. Lots of researchers are trying to write a computer code which can simulate brain function on standard computer. These researchers have to use big machines which use enormous power to operate. But Williams suggests using hardware instead of computer code to simulate human brain. This hardware is made of memristor which can reduce the complexity of human brain simulator.

How does touch screen work?

Touch screen is very amazing invention which reduces the space occupied by the keypad in the mobile gadgets. As a result the gadgets are being more compact in size and the display is being bigger. Touch screen has become so popular that most of the new gadgets being launched is using a touch sensible display.

After using a touch sensible display a tech geek would wonder how is this working? What type of circuitry is used in this display? I would tell you how touch screen works in this article.

A touch screen is a two dimensional sensing device which is made of two sheets of material separated by small spacers. Generally a sheet of glass is used as a bottom layer and a sheet of Polyethylene(PET) is used as a top layer. Polyethylene is a flexible material.

These two sheets are covered with a resistive substance which is usually a metal compound named Indium Tin Oxide (ITO). Thin layer of ITO is uniformly spreaded onto each glass and PET layer. Small bumps named spacer dots are added onto the glass over the resistive coating. This spacer dots creates space between two layers and prevents accidental or a false touch.

When someone touches the display, the PET film is pressed down so the two resistive surfaces touch each other which completes the circuit. The position of this touch can be calculated by a touch screen controller circuit.

The controller circuit uses two dimensional system to determine the point of touch. The basic two dimensional system is shown in the figure.

By measuring the value of X and Y you can determine the position of touch.

In a touch screen display there is two different circuit for measurement of X and Y position. The circuit for measuring X position is shown in the below figure.

As you can see from the figure that there is different value of resistance for each point on the X line. By measuring the value of this resistance you can determine the X position.

The circuit for measuring Y position is shown in figure.

The function of this circuit is also same as the circuit for X position. As you can see from the figure that there is different value of resistance for each point on the Y line. By measuring the value of this resistance you can determine the Y position.

Thus the controller circuit can determine the position of touch in the display.