Bluetooth V/s Cellphone

One of the favorite electronic device I love to have is bluetooth stereo headset. Though I am fancy about it, I wanted to know which one is worst between cellphone and bluetooth. I did questions about it with many guys but there nothing is conceivable. 

Many electronics and communications engineers argued that bluetooth is of a higher frequency(2.4GHz) and mobile is of low frequency(800MHz -2100MHz) and hence mobile is more safer than BT. 

But in reality, the frequency is not the matter of concern* , only the power matters. The power radiated by a BT headset is 0dBm(1mW)  where as a mobile set will radiate up to 33dBm(2W).The power radiated by a mobile set depends on the distance between the tower and mobile set. Though we are not talking in the cellphone, the cellphone will continuously communicate with  the tower to register its presence within the cell(a radiation circle where one tower influences on the device). Weaker the signal received by the cellphone, it will boost the signal level to communicate with tower.

Also my thinking is that, if the cell phone is close to the body, the body capacitance also influence on the power as signal will couple more to the body rather than reaching the tower.(discussion needed). 

Hence, it is better to use bluetooth headset and it is not good to hold the mobile set near to your body (either close to ears/in pockets).

One interesting fact, though frequency is not a matter of concern, in case of bluetooth frequency has one special case. It happened that the natural frequency of water molecule is also 2450MHz(source:http://www.esato.com/archive/t.php/t-29390,1.html). This coincidence frequencies  create heat effect in the body flesh. Read above link for details. 

Finally, bluetooth rocks, please close your white teeth...~:)

List of Books- softcopy available

Books available click here to see the list:

PS:Don't request a book in Mail.

Online passwords how and where?

         I was hearing an incident of hacking of email password of one of my colleagues in the office.He used his email password as his account password with a music site. The hacker hacked his email password.I thought to write about it as many people also not aware of some facts in online surfing. 

In on-line browsing your email id is your identity. It is unique.Never trust an email id unless you have exchanged id  physically or any other secure communication. 

In online world, we have two kinds of accounts. One is account with mail service providers and one with other service providers. The gmail,yahoomail,hotmail...etc are email accounts, where as accounts with ebay,railway booking,ksrtc booking,any music site account...etc  are service accounts. The service account is not at all to give an email id which you can share with your friends/colleagues or add to office data. However, they allow specific communication with respect their service is concerned.

Generally, service accounts ask you to register first time. You need to have email id and and other info. Along with this info, you need to enter password. Which one will you enter ? or email password or something new password?.

Never ,ever enter your email account password. I hope,we hope,every one hope that email accounts providers will not cheat us. They will not take our account data.Hence,email id are unique identity in the virtual world of INTERNET.

Since we are registering same email id with many service accounts and (with email)password, if any fake service account provider hack our email we can not access email account and or any service account any more.

The lose of  your email account is not a simple lose ! In order to make you clear,please note that email account creation needs more information than your service accounts. If your account is used by any one for illegal activities, you will be liable. So,we need to give importance to email accounts as same as we give it to SIM cards.

No bank can ask you any information through email.Such kind of mails are considered as spam. Just delete them or inform to your bank. but never respond.

Another big scandals of this day are online lottery announcement/fund transfer email.These kind of emails are very interesting to read and if you give attention to them you will loose lakhs of rupees.Always believe that  " No one can give you money freely in this world".

I hope this info is good to you.  

Udayavani Download-Perl Script

I always read Udayavani. I read Udayvani to understand the cultural and social face of Udupi. It is almost "pakka" that my permanent nest will be in Udupi. (extra to main topic)..

I read the paper online in the link: http://epaper.udayavani.com/. I had a problem here:After reading first page, I needed to wait sometime to download second page and so on. Most of the time I got irritate with this. In order to solve the problem, I used a small script which download the whole paper to the desktop directory.

Nb: There is nothing special in this code. Just(Junk) do it(JDI).

The perl code is here
#### New udayavani, with self date and directory of download.
###date 10/09/2011.

print "===================================\n
Welcome to Udayavani e-paper
\n===================================\n";

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime(time);
$dd=$mday;
$mm=$mon+1;
$yy=$year+1900;
print "Date:",$dd,"-",$mm,"-",$yy,"\n";
print "\n===================================\n";

#=====Date conversion
if ($dd<10){
@day[0]=0;
@day[1]=$dd;
}
else{
@sdd=split(//,$dd);
@day[0]=@sdd[0];
@day[1]=@sdd[1];
}
#=== @day;

#==========month conversion;
if ($mm<10){
@month[0]=0;
@month[1]=$mm;
}
else{
@smm=split(//,$mm);
@month[0]=@smm[0];
@month[1]=@smm[1];
}
#===@month;
#=================year conversion;
@syy=split(//,$yy);
shift(@syy);
shift(@syy);
$date=@day[0].@day[1].@month[0].@month[1].@syy[0].@syy[1];
#print "\n\n", $date,"\n\n"; converted value.


#========download converion for links
@letters=split(//,$date);
$date_part="2011-".@letters[2].@letters[3]."-".@letters[0].@letters[1];
$j=0;
for($i=1;$i<17;$i++){
if($i<10){
@letters[9]=0;
@letters[10]=$i;
}
else{
@letters[9]=1;
@letters[10]=$j;
$j=$j+1;
}
#print @letters,"\n";
$pageName=join("",@letters);
$pageName="Man".$pageName."M.pdf";
$link="http://epaper.udayavani.com/PDF/MANIPAL/".$date_part."\/".$pageName;
print $link,"\n";
#print $pageName;
system("wget --directory-prefix=/home/venkat/Desktop/Udayavani $link");
}

====end of the code =====

Audio Volume-In noisy environments

Hello,

While roaming with Motorola s305 stereo headset, I conceived an idea!
Many times, we need to be in different environments/surroundings where noise level is not constant. If we are listening music in the cool surroundings the volume of the audio may be 5% of the maximum, however, if we are in market area we may need to raise it to 100%.

Since surrounding noise(also called as ambient noise) greatly influence on the volume of audio we like to have. My idea is why we should not design a volume controller such that volume of audio automatically increases or decreased depending on the ambient noise level ?  

There is some kind of technique called ANC-Active Noise Cancellations (http://en.wikipedia.org/wiki/Active_noise_control). But I failed to understand whether I am talking is ANC in different way?

Bluetooth and Wifi

Hello, welcome to wire'less' world. I recently bought Motorola S305 bluetooth stereo headset. It is good one..!Enjoying.

   I have android G-i5801,samsung galaxy 3 mobile. Interesting thing is that it has wifi,bluetooth and lots of application (available in android market). 

My head cracked yesterday..! You know why, battery is 60% in  half an hour!! Before having headset I was to use only wifi and now adding bluetooth stereo headset, the mobile is more power hungry. 

I am thinking, if  wifi and bluetooth are of operating at  same frequency(with different protocols:it is a group of software programs which controls the hardware) why can not both share the same hardware? If we are able to share the hardware,whatever, complexity within the protocols can be compromised in the coding. I believe that if we make some changes in design, wifi can acts a bluetooth or wifi with a single hardware. Power will be saved, silicon area will be saved, $s will be saved.

Anybody have counter argument for this? Your suggestions are most welcomed.

Scientific Calculator

web 2.0 scientific calculator

Power on reset

Power on reset is an essential requirement for sequential circuit based modules. We consider a simple example, consider a remote controlled tube light or fan system, the circuit of interest is shown in below image.

The IR Rx is a infrared Receiver which trigger the DFF and switch ON/OFF the fan depending previous state of the DFF. The circuit is practically laid down on the PCB and is working fine. However, when the power is turned on some time the fan ON and some time OFF. It has happened that when supply  line is goes off, and supply arrive later the fan can turn on automatically. The problem is the DFF can attain logic high or low state and was unpredictable. 

In order to solve the problem, we need power on reset. Here R and C in the circuit do the job.

Whenever power is turned ON, while charging the capacitor, there is a current passing through the resistor and hence voltage across the resistor. This voltage uphold the reset pin of the DFF. The by selecting proper R and C values we can meet the reset condition of the DFF.After charging the capacitor C completely, reset pin is  grounded as there is no current through resistor. 

Very simple!

Communication within 10cm!

Who will not laugh at me if I say "There is a system which communicate in the range less than 10cm..!" Do we need a system or device to communicate within 10cm? what a stupid idea...!?

Sorry, I am confident and don't mistaken me. I am talking about the communication within 10cm only. Oh...that is new wireless communication called NFC. 

Before talking about NFC, I will give an example. You go to a  city and looking for roadside candy for Rs.7. You have 500/-  and no change. You have to roam here and there to have change for 500/- or candywala needs to give change for you. I have experienced that both the ways are difficult.

You believe me, you have one more choice now.  "Just hold your mobile very near to candywala's mobile..and take candy in your hand..that's all".

Yes, that is possible in few years. The new wireless communication system called Near field communication(NFC) is developed for mobile and alike devices for secure transactions, business card exchange and may be for identity as well.

The NFC is not made for file sharing and huge data transfer protocol like wifi or bluetooth. Since the range is less than 10cm, inherently secure than other wireless technology. 

NFC is a extension of RFID. An RFID system operate in wide range of frequencies. However, an NFC system is standardized to 13.56MHz.Since many frequency bands are already allocated to different functions in different countries by FCC, only 13.56MHz is freely available band.It is also noted that this band of frequency is also good enough to meet VLSI design standards(lower the frequencies bulkier is the systems and higher the frequencies power will be high).

Recently released android mobile Nexus -S has NFC. The NFC usage is not yet grown enough to build trust in the society.Tech news sites have reported that 6 out 10 multimedia sets will have NFC by 2015. 

I will happily welcome you NFC..! 

Trainer is not a 'train' but a Teacher

"Teaching is the best way to learn". I too believe this statement. If we read the books,paper or INTERNET pages any subject is felt like so simple!!!. I believe that knowledge of a person is valuable if he practically makes a material out of it and able to transfer the same to the next people. In order to maintain richness of knowledge base industry every one needs to be trainer and trainee. I am good trainee and wanted to be a good trainer....i.e, BOTH.

I was to much enthusiast to become a trainer and I did many kind of testings at the beginning itself. The test cases which I did and aftermath of them are listed below:

1. I wanted every one to be on time to classes(punctuality).
2. The trainees need to be happy and comfortable.
3. The technical matter should be discussed in way that enthrall the class, however, the technicality of any concept should not be wrongly taught.
4. Do mistakes, but agree to mistakes rather than some one forces us to agree.
5. In technical discussions, no matter who/what/where/when talks, if something is wrong raise the doubt and question it for clarifications.
6. Have a good friendship with trainees.
7. Explain the subject with examples where everyone can understand the things well.
8. Be a free teacher, who is available all the time-in messages, chats, emails, class or lunch or dinner table.
   
9. If the class is not going in the directions as expected, entertain the trainees by asking their hobbies and presenting them(like singing..jokes...shayirees...)Come back to technical with relaxed mind.
10. Not to be strict on assignments, but convince the trainees about their responsibility.

However, I failed in some of the things-

• Some time, we need to stop questioning the people even if they are doing wrong as their ego may hurt and it may start bleeding.
• Very critical-never have friendship with trainees. We can not teach friends,but be friendly.
• Not to be available freely. There is no respect for things which comes free..!
• Technical classes, needs to be completely technical(for point-9), I did not understand, why people separate technical stuff from other stuffs?
• Assignment-we needs to be strict.

Any way, every day is a new learning assignment and I use past history for betterment of self and surroundings. I am confident for training once again with modifying wrongs things of past training.

I would like to take an opportunity here to thanks all the trainees, who have enjoyed my training and those who suffered because of my tests.

Noise about "NOISE" in circuits

Hello, who never heard of noise in integrated circuits(IC)..!...white noise,Gaussian noise, flicker noise, 1/f noise and so many different terminologies. I can talk about NOISE and make some noise and I agree that I don't know exactly about what are these dirty noise in my systems is. However, there are noise in systems which are internal to the system and some which are influenced by the external world like-another circuit besides it, environmental radiations etc.

I have a confusion -whether noise is positive or negative with respect to ground?

We operate circuits with positive supply(with respect to ground).NB:ground is decided by the battery and not by circuit). However, it is important to have proper ground and supply connection to a circuit.

If we operate a circuit (say CMOS inverter) with following topology(shown in image right side one),do we get any advantage over the noise performance?

No doubt, the input of for the new topology also be need to change with respect new reference.However, are we achieving any thing good here. It is one of  the thought in opposite to classical definition of reference and ground.

Let me know your views. Comment please.

Ubuntu:What is special about it?

Every engineer, whatever his/her branch of studies, will aware of computers.When there is a computer, there will be  windows OS. But now the situation is changing. People are moving towards free software/open source softwares. Ubuntu is one of such free OS and almost graphically look like windows.I can say good competitor for windows.  

All people are biased with windows and say linux is not user friendly. I believe that Ubuntu is exceptional with respect to user friendliness and with engineers view- it  is far.. far.. better than windows. 

What are the advantages of ubunut?

1. No virus(Every OS can be hacked, but it very less chance for linux OS systems).
2. Completely free.In 2010, Ubuntu has freely provided the OS cds. Now any one can download from here.(10.04 is good one. recently 11.04 stable version released).
3. One time installation; you will get all softwares-No separate installation for drivers, adobe reader,open office,audio players, video players, games,.....never ending list. If you need any software jut search in "Ubuntu Software Center".
4. Engineers have very good deals with Ubuntu. We can change the systems the way we wanted it to be.All kind of languages-Perl, C ...etc are inherently inbuilt. Also for circuit enthusiasts-PCB design, VLSI design, SPICE simulation tools are also available.
5. Recently computers are coming with higher memory hard disk and RAMs and hence no trouble with speed or OS size.

Demerits:

1. We all have background of windows and we refrain ourselves from looking an OS other than windows angle.
2. Installations of software is little bit tricky in linux- No simple click !
3. I suggest the beginners to talk about basics of linux with anybody who knows about linux.
4. For property devices - for mobile, ipod, mp3 players no drivers available in linux. This is the only one worry that will make us to keep a copy of windows in our systems.

Some facts about Ubuntu:

1. Brazil is completely linux-ised.
2. Kerala government school supports linux(Read here)
3. 100% on line supporting community.
4. Live CD boot-able options.
5. If your windows got "viral infection and died", then Ubuntu live CD is only way (As I know)to recover your data.

I welcome you all for Ubuntu OS.Ubuntu is made for human beings..!

Idle time in office != free time

Most of the time, we need to be idle state in the office. Either it may be waiting for inputs from senior colleagues,waiting for some one to finish their work as my work is linked to their work, network is down, my computer is taking lot of time and I need to refrain from interacting with it or may be most dangerous situation when I need to wait for next task to be assigned. In such situation, I always think, I need to use the time for reading at least a page of technical stuff.

However,I felt like, it is impossible to use the idle time for any fruitful activity.The reality  is we will not be aware of when we will be idle and how much time we will be idle.Hence, there will not be any planned activity. When I come to know that I need to be idle state, I will be confused what to do, what to read, so many things. Later,having lots of alternatives,nothing will be selected and completely in confusion through out the idle time. Idle time is most boring and unhappy situation in the office.

Idle time forces many people to roam here and there and talk about not related to office subjects like-crickets, PJs(Poor Jokes) and long lasting tea breaks. At the end of the day, conclusion is only one:day is passed without using the time economically. 

I don't know how many people have felt in this way. Unfortunately I had/have faced this vicious situations. Can anybody advise me how to use idle time? 

Pumpset electricity bill-'HOW TO' for rented houses?

Day by day energy(petrol, electricity) related bill per month are increasing in huge amount.Every one is trying to reduce the power consumption as well as very cautious about the energy bills. 

Many people are  staying in rented houses and many people are giving there houses for rent.Now each rented house also has an electricity meter, however,owner and renters needed to share common pump set and  share electricity bill at the end of the month. Many times, the renters may be single(like me...!) or big families. Hence, it is difficult to calculate who used more water or(indirectly) who used more electricity.

My colleague Chetu (Chetan G) had trouble in renting his house in his native  with a single water pump. "Venky, namamaneyaga water pump set problem ide...enadru madala...!". The problem given by chetu is exciting one. 

After scratching my head for few hours, I came up with control circuit which can share the single water pump and directly energy consumption is recorded in respective meter of the house/rented rooms. The overview of the system is shown in below image:

I need few components, which related to mechanical assemblies, looking forward from some dealers in Bangalore.The microelectronics components are very costly in udupi and many of them are not available here.

I hope, I will be able to release the complete system as simple product for every house hold where everyone share the same water pump without fighting for electricity bill.

I thank our Chetu for bringing such problem in front of me. 

Anode or Cathode?

This is a confusing thing to talk... isn't it? Ya..

The cathode is the terminal where the current always flowing out of it. For example, the electrode of the battery (while discharging ) acts as a cathode as it is giving out the current and a positive terminal. However, same electrode acts as a anode while recharging the battery. Cathode and Anode terminologies need to use very carefully. 

In normal diode (P-N junctions) the P acts an anode and N acts as a cathode.Here, we believe that forward current is considered. However, in case of zenner or solar cell, there is no significance for forward currents. They working principle is  reversed junctions.But, still we use the terminologies of the normal diodes. 

I am thinking, which terminal is anode and cathode of schotkky diode...?  'Art of analog layout' says "Metal acts as anode and silicon acts as cathode".Is it same for both P-type and metal junction and N-type and metal junction? 

Finally, I am confused..! bye.

LTSPICE: A tool for Electronics engineer

Hello, I think most of the engineers know the tool called LT-SPICE. LT-SPICE is a free electronic schematic capture and SPICE simulation tool.This tool is developed for analysis of switching regulators by Linear Technology Inc.

LTSPICE is originally windows OS based tool, however,in linux under wine support it works fine.Very important thing about LTSPICE is not only a free tool but also ability to modify the things(not software) in a way that we needed. We can add external components to existing default library. Under simulation we can process the data files with ngspice as a background tool. We can add our own models.The option to make unlimited sub circuits hierarchy is appreciable.The help content is available in help file, yahoo forum, and LT-SPICE user guide.

If we compare other electronics tools-electronics workbench, circuit simulator,microcap,TINA...etc, we have very less options or more constrains imposed by the software vendors.

I hope everyone will enjoy this tool for their electronic simulations.Some extent,I can also help you out on LT-SPICE.

Audio amplifier:inverting or non-inverting ?

Hello dear friends.
We know that op-amp can be used as inverting or non-inverting configuration. The basic configuration is shown in figure 1.The only difference between the two operation is change in phase between the input to output signal.

Figure 1:Op-Amp basic inverting and non-inverting configurations.

I have one question about these op-amp configurations:
If we give input audio signal (Example:in figure 2), with both are designed for same gain, what would be the quality impact on your ears? Which would be better configuration?

Figure :2 audio signal

Many people have given me very crazy answers. Some one told me that your words will be reversed?(impossible one!). Some one argued that signal will be delayed, and many more argued it is immaterial with respect effect on ears but design-wise we may have one configuration better than other.

Finally, conclusion not yet reached. Any one can post me if you have good answers. I will place the components on breadboard and test one day and result will be declared here.

NMOS @GND and Weak "1" transfer

We always use PMOS connected to VDD (or vdd side) and NMOS connected to gnd(or gnd side).
Example, in the inverter circuit PMOS is always connected to VDD and NMOS connected to GND.

Now,
1.What happens if we change NMOS and PMOS positions?
2.What is the problem in digital design with new topology(example: inverter)?
3.What is the problem in analog design with new topology(example:amplifier or current mirror)?

A pdf written by me is available on this subject in the link here

Ubuntu:Audio converter

Audio converter is tool which more often used by me for conversion of audio for mobile,iPOD and so on. Here is a link for ubuntu OS, explained very well.

http://ubuntuforums.org/showthread.php?t=712064

It is good to post here, at least for my reference in the future.

MOSFET amplifies the signals ONLY in Saturation Region Part-1

Yes, mosfet can be used as amplifier in saturation region. It is should not be forget that transistor shows highest gain in sub-threshold conduction. However, sub threshold conduction operation is not yet practical. 

We can show the amplification property of transistor in saturation region by two ways:1).Analytical method and 2).Graphical method. In this post, we discuss about the analytical method.