Private India

Title: Private India

Author: James Patterson & Ashwin Sanghi

Pages: 480

Publisher: Random House

Why i picked up this book:I have previously read 'Chanakya's Chant' by Ashwin Sanghi and

enjoyed reading it,had given it 4/5 stars on goodreads if I remember correctly.

(I had also read an excerpt of 'The Krishna Key' by Ashwin Sanghi).

So I was looking forward to read Ashwin Sanghi's next and when it was in collaboration with James Patterson,I just grabbed it.And in any case i like reading thrillers.This book is certainly a murder mystery/suspense thriller genre and i enjoyed reading it.

The story is set in Mumbai during the week of Navrathri where the plot unravels and it grips you in its hold pretty much from the beginning of the book.
Santosh Wagh,the protagonist,an ex-cop is the chief of PRIVATE INDIA,Mumbai branch of one of the best detective agencies in the world.Wagh is a middle aged guy who is addicted to alcohol and is almost always drawn to a bottle of Johnnie Walker whenever it comes within his sight.Sporting a salt and pepper stubble and walking with a psychosomatic limb. Facing nightmares about his troubled past but brilliant at his job as private detective is called into action right at the beginning when a body is found in the bathroom of room no.1121 at Marine bay plaza hotel.The dead body was identified as Dr.Kanya Jaiyen,found with a yellow scarf around her neck and hands tied with a string with a lotus flower in the right hand and a fork in the left,also a toy Viking helmet tied to a toe. Then.. there is a series of murders(all women) with the same yellow scarf around the neck and some props carefully placed in and around the body.
Why is the killer killing only women? Why is his method of killing is to strangulate using a yellow scarf? What's all the props/clues that the killer leaves behind?Do they tell a story? 
Santosh Wagh and his team at private India must solve the case and fast,otherwise God knows(or may be Santosh Wagh does know!) how many more women with a yellow scarf around their neck will be found dead.
There is a sub plot with the Indian Mujaheddin acting on the orders of ISI trying to destroy PRIVATE INDIA.

They say,murder mystery/suspense thriller must keep you guessing as to 'who the killer is?' or 'what will happen next?'.'Private India' most certainly kept me guessing throughout.My suspicion moved from one character to another until it reveals itself in the book.I completely loved reading this one.The climax is quite thrilling with a twist which is hard to guess!

The action involving Jack morgan and Munna(Mafia don) in the climax is quite unneccessary and a little too filmy or atleast felt so.

I strongly recommend this,you will love it, or at worst you won't be disappointed. That's for sure.

Characters that i liked/ found interesting: The entire PRIVATE INDIA team.
Nisha Gandhe-assistant /next in command to Wagh , beautiful middle aged women,an ex-cop married to stock market guy with a little daughter.A charming character.
Hari Padhi-'tech geek' of PRIVATE INDIA is also a very likeable character with some very interesting bit of history attached to him(typical of Sanghi to blend history into his story/characters, he ssems to that effortlessly and its very believable too).
You'll like this guy and also feel bad for him as you read along.
Mubeen-the forensic expert of PRIVATE INDIA who also has troubled past similar to Wagh in certain respects.
Jack Morgan-an ex-marine in US, the founder of agency PRIVATE.

Rating: 8.5/10

ALL ABOUT THYRISTORS-2

ALL ABOUT THYRISTORS-2

(I will be taking a slight deviation from book review blogposts.In this post,will be trying to explain an electronic topic "Thyristor" in a simple way. Hope all of you who are interested read and learn about the topic.Enjoy!
I will be posting it in 2 parts. The first part contains History,construction and operation of 'thyristor'.)

In part 2 of this post,you will find concept of thyristor turn ON,Effect of gate current,Types and Applications.

Turning ON of Thyristor:

So inorder to turn on a 'thyristor', we need to increase the anode-cathode voltage above 'breakdown voltage'.But practically if you do so, you will end up burning the 'thyristor'!Huh..!You don't want to do that right?
Manufacturers specify the voltage limits(dv/dt limitations) and care should be taken not to exceed this limit. So to avoid risks of burning the 'thyristor' a different method should be opted which involves the use of gate terminal.Have you noticed that I haven't used the gate terminal after mentioning it in the 3 terminals of 'thyristor'? Gate terminal has a very important role in the process of turning the 'thyristor' on. So all you need to do is,apply a small voltage(mostly pulses) at the gate terminal and now start increasing anode-cathode voltage.Guess what happens!? When you apply gate voltage, 'forward breakdown voltage' decreases. In other words, gate voltage is inversely proportional to breakdown voltage. This avoids the risk of burning the 'thyristor'. Eventhough you remove the voltage applied to gate terminal now,'thyristor' continues to conduct.It can be brought back to non-conducting state only by reducing the forward current below holding current.

Effect of gate current on breakdown voltage:

As gate current increases from IG1 to IG2,forward breakdown voltage decreases
from v1 to v2.

Thus by increasing the gate voltage, 'breakdown voltage' can be decreased. The applied signal to the 'gate' terminal should be removed once the 'thyristor' is turned on. If not,it results in excess power loss.Hence it is better to prevent the losses.

NOTE: From the v-i characteristics of a 'thyristor', note that a 'thyristor' allows the current to flow only in forward direction i.e., thyristor is an unidirectional conductor.But a type of 'thyristor' named 'TRIAC' is birectional which conducts in 2 directions.

Types of Thyristors: There are a total of 13 types of 'thyristors' which are as follows:
1)Gate Turn Off Thyristors(GTO's)
2)Fast switching thyristors
3)Phase Controlled Thyristor(or SCR's)
4)Light-activated Silicon Controlled Rectifiers(LASCR's)
5)FET-controlled thyristors(FET-CTHs)
6)MOS controlled thyristor(MCTs)
7)MOS-turn off thyristors(MTOs)
8)Birectional triode thyristor(TRIAC)
9)Bidirectional phase-controlled thyristors(BCTs)
10)Emitter turn-off thyristor(ETOs)
11)Integrated gate-commutated thyristor(IGCT)
12)Static Induction thyristor(SITH)
13)Reverse-conducting thyristors(RCTs)

Applications of Thyristor:
'Thyristor' has abundant applications in today's rapidly growing Power Electronics field.It is used in most of the Power circuits.

• Thyristor is widely used as a switch as its ON and OFF conditions can be controlled.
• Thyristors are used in AC voltage controllers which inturn are employed in Induction motors to vary the speed by varying output voltage.
• Thyristors can handle high power.In other words they have good power handling capability because of which they are used to control power in many circuits.
• Commonly thyristors are used in light dimmers,fans etc.

Thyristors are majorly used by soldering them into IC's(Integrated Chips).

How Thyristors are superior to Transistors?
Though 'thyristors' and 'transistors' have their own applications,'thyristors' are more useful in quite a few ways compared to 'transistors'.

• The basic advantage of thyristors is that,unlike transistors, their ON-OFF can be controlled.
• Thyristors have high power handling capability than transistors.

Also there is low power loss in thyristors compared to transistors.

Why thyristor is also called SCR(Silicon controlled Rectifier)?
The reason thyristor was earlier called as SCR is this- 'silicon' simply because it is made up of semi-conductor silicon and it basically acts as rectifier whose operation can be controlled.Hence the name 'Silicon Controlled Rectifier'.

-Pooja.

ALL ABOUT THYRISTORS-1

ALL ABOUT THYRISTORS-1

I will be taking a slight deviation from book review blogposts.In this post,will be trying to explain an electronic topic "Thyristor" in a simple way. Hope all of you who are interested read and learn about the topic.Enjoy!

I will be posting it in 2 parts. The first part contains History,construction and operation of 'thyristor'.

There are two ways of learning anything. First one: 'Thyristor' is a 4 layer power semiconductor device having 3 terminals namely anode,cathode & gate.And it has a PNPN structure i.e., it has 3 p-n junctions.There are 13 types of Thyristor.... This is certainly what is given in the textbooks you refer or your lecturers expect you to write in examination! Well,this is one way of learning and this doesn't seem like learning to me. One can possibly learn anything only if he/she can understand particular topic.
Now, I am going the second way which is easier. I have tried to provide a step by step explaination of 'thyristors' followed by its vast applications(in part 2).

HISTORY: The cocept of thyristor was first proposed by William Shockley in the year 1950. With the rapid increase in Power Electronics, commercial thyristors were soon introduced in 1950's.Then,it was popularly called as 'silicon controlled rectifier(SCR)'.The reason for this is in the later part of the post(in part 2).

Why the name 'thyristor'?: 'Thyristor' is a combination of two words- 'Thyratron' & 'transistor'. A 'transistor' is again a combination of two words- transfer and resistance. 'Thyratron' is a type of gas filled tube. It is basically a controlled gas rectifier.Thus 'thyristors' have applications of thyratron in addition to what transistors have.

Construction: 'Thyristors' are manufactured by the process of diffusion. It has three p-n junctions forming four layers. Hence it is said to have PNPN structure. It has three terminals namely anode,cathode and gate.It acts as a bistable switch i.e., a 'thyristor' can be either in conducting state or non-conducting state.Since its ON & OFF conditions can be controlled, it can be used as a switch. The symbolic representation and view of p-n junctions is shown below:

  

        

Operation: It can be observed in the figure that 'thyristor' has 3 terminals and 3 p-n junctions. Once anode terminal is made more positive compared to cathode terminal,junctions J1 and J3 will be forward biased.Whereas junction J2 will be reverse biased. As a result,only small amount of current i.e., leakage current flows.Under this condition,'thyristor' is said to be in "forward blocking" or "off state" condition. In order to bring the 'thyristor' in ON state, anode to cathode voltage needs to be increased. When we keep increasing the anode-cathode voltage, at particular value of anode-cathode voltage 'avalanche breakdown' occurs. (Avanlanche Breakdown: Eventhough reverse current does not depend on reverse voltage, if reverse voltage is increased to sufficiently large value,velocity of minority carriers increases.Due to kinetic energy associated with minority carriers,some more of them get generated on colliding with other atoms.In this way carrier multiplication takes place and minority carriers get accelerated due to high reverse voltage.Thus a large reverse current flows. This effect is called 'Avalanche effect').Here since junction J2 is reverse biased,anode to cathode voltage acts as reverse voltage to J2.Hence junction J2 breaks when anode-cathode voltage is increased to particular value. Now the carriers can move freely in all the 3 junctions and large anode current will flow. In this condition,'thyristor' is said to be in "on state" or "conducting state". The value of anode-cathode voltage at which avalanche breakdown occurs is called "forward breakdown voltage". The operation of a 'thyristor' can be understood by looking at its v-i characteristics.

It can be analysed from the v-i characteristics that when anode-cathode voltage is below 'forward breakdown voltage',only a small leakage current flows. And 'thyristor' enters to conducting mode once anode-cathode voltage reaches 'breakdown voltage'.

'Latching current' and 'Holding current' are the two new terms that can be observed in the figure above.

Latching current(IL): A minimum amount of current is required to bring the 'thyristor' from non-conducting state to conducting state. This current is defined as Latching current.

Holding current(IH): Once the 'thyristor' is in conducting mode, if the forward current decreases below certain value of current called 'holding current', then the 'thyristor' stops conducting.In other words, 'Holding current' is the minimum current required to maintain the 'thyristor' in ON state condition.

Many of them confuse the 'latching current' with the 'holding current'. But its very important ot know the difference between these two.


-Pooja.

Bankerupt

Title: Bankerupt

Author: Ravi Subramanian

Publisher: Penguin India

Pages: 319

Publication year: 2013 January

I had been thinking of reading a book by Ravi Subramanian ever since I got to know he's known as the 'John Grisham of banking','India's John Grisham'. And when I felt like reading a thriller -picked up "BANKERUPT' by Ravi Subramanian and it was one heck of a ride.

Its quite difficult to write a summary of this book as there are more than one stream running for a majority of the book and in the end they converge to provide one heck of a climax.

Right at the beginning of the book,in the second chapter-a woman is lying dead in the Boston Public garden. No signs of  injury on her body, is it only a tired jogger who suffered a heart attack? Or there is something more to this? This is only the beginning(also the end!?) of all the thrills and spills in this book.

Cirisha Narayan is an extremely honest and upright woman working as an assistant professor in Social Pshycology department of MIT (Massachussets Institute of Technology), Boston.

Aditya Raisinghania is an ambitious but greedy investment banker at Greater Boston Global Bank(GB2), who gets his hands dirty getting involved in all sorts of fraudulent ways along with his friend Shivinder Singh. Ultimately pays the price for it and is sacked.

Once Aditya moves to Boston after getting sacked to live with Cirisha, the story moves into top gear advancing at a rapid pace and you just cannot put the book down until you finish it. Its an emotional roller coaster ride, you can hear your heartbeats quite loud at this stage.

Another subplot is the power struggle between two superpowers of MIT, Micheal Cardoza and James Deahl. Somewhere along the line Cirisha gets caught in all of this following the death of her dear friend Richard Avendon, an assistant professor at MIT desperate to get his tenure.

Its hard to put down thriller with the story moving at a rapid speed with short and crisp chapters throughout. A must read if you are wanting to read a thriller, you'll enjoy the ride. 

Guranteed!

Rating: 8/10

Title:The Immortals of Meluha

Author:Amish Tripathi

Publisher: Westland

Pages: 411 

'When evil reaches epic proportions, when all seems lost, when it appears that your enemies have triumphed, a hero will emerge'.

One of the best books i have recently read is "The Immortals of Meluha" by Amish Tripathi, the first book in the Shiva Trilogy(second and third being "The Secret of the Nagas" and "The Oath of the Vayuputras").

              

The story is set in 1900 B.C in the land of Meluha(Indus valley civilization). 

The story begins with Shiva coming to Meluha along with his tribal camp on being invited by Meluhans. Meluha is an empire created by Lord Rama which is near perfect in all the ways. The inhabitants of Meluha i.e., 'Suryavanshis' are waiting for Neelkanth to arrive and save them from the attacks of 'Chandravanshis' who have allied themselves with the Nagas(Serpents),a sinister race of deformed humans possesing astonishing martial art skills.

What i liked the most is depiction of Lord Shiva as a common man who becomes Mahadev,the God of Gods. Shiva speaking the language of a common man using the words 'bloody hell', 'damn', 'goddamit' etc makes him a cool dude and that makes reading the book more interesting.

The story is fast paced with one event  leading to another which makes the book unputdownable. The ending of the book will force you to quickly jump to next book in the trilogy- "The Secret of the Nagas".

Rating: 8/10

Highly recommended.

- Pooja 

 !Hello everyone

I had been thinking about blogging since quite a while and finally have made up my mind and starting this blog.

Mostly, I will be blogging about books(reviews of books i have read in the past or those books i will finish reading in the future).Maybe a little bit about Cricket,Technology,Movies,Food recipes etc etc.

Please read and leave your comments to let me know 'Did you like the blog? Or not'.

Thanks.