Archive for March 2013

wireless charging technology

Sunday, 17 March 2013
Posted by AVINASH CHAKRAVARTHI
Its no more science fiction...it came into exist...we need to know how it rules our future & how it works????
million of answers available in internet for the question " how it works?"..
thousands of videos on YouTube demonstrates the  wireless charging..
yet.....there is a question" how it actually works ?"
here we go...i will promise u ." u will learn at least 5 % on  how it works and u will make u r own wireless charger for u r gadgets .."

1.what is wireless charging?

        

      2. how it works?

     Wireless charging, also known as inductive charging, is based on a few simple principles. The technology     requires two coils: a transmitter and a receiver. An alternating current is passed through the transmitter coil, generating a magnetic field. This in turn induces a voltage in the receiver coil; this can be used to power a mobile device or charge a battery.
        
    •     explanation with block diagram

     
             both transmitter (TX) and receiver (Rx) coils are made up of copper coil.
             rectifier is used to convert the ac signal to dc signals.

    3basic principle and it's efficiency  factors:-

        As i already told u ,the principle is mutual induction between the TX and receiver coil
        let the induction of TX coil is L1  ,
                   inductance of RX coil is Rx,
                  distance between the coils are Z,
                  diameter of TX and RX coil be D1 and D2.
    •   the efficiency of the wireless power transmission depends on the  1, coupling factor
                                                                                                                                 2, quality factor
          
      A. COUPLING FACTOR:-
     The coupling is determined by the distance between the inductors (z) and the relative size (D2 /D1). The coupling is further determined by the shape of the coils and the angle between them 
    • The efficiency drops dramatically at larger distance (z/D > 1) or at a large size difference of the coil (D2/D1 < 0.3)
    • A high efficiency (>90%) can be achieved at close distance (z/D < 0.1) and for coils of similar size (D2/D = 0.5..1)


    B. QUALITY FACTOR:-
    The ratio of the inductance L to the resistance R of a coil remains constant for different winding arrangements in the same volume and shape. It makes sense to define this value as a figure of merit to distinguish different coil structures. The quality factor Q is defined by this ratio.The voltage, which is induced by the same current in an inductor scales with the frequency f and thus the apparent power in the device.

    The general definition of the quality factor is based on the ratio of apparent power to the power losses in a device


    Remember quality factor is not under our control it is designed by the manufacturer  
     the value of quality factor will be 0 to infinity,For mass production you may expect values around 100

    4. calculation for getting max efficiency:-


    The power losses while transmission can be expressed as loss factor




    which is the sum of all losses related to the transferred power. A deeper analysis results in an minimum loss factor, which can be achieved by a given wireless power system, if it is proper matched to load and generator:
      





    Which can be reduced to:




     
    The equation is only dependent on the two basic parameters of the wireless power system: The coupling factor k between the receiver and transmitter coil and the system quality factor Q. The system quality factor is the geometrical average of the transmitter’s and receiver’s quality factors.


    • This means, that the system quality factor and the coupling factor determine the performance in an equivalent way. A worse coupling can be linearly compensated by a better quality factor and vice versa.



    BLAH BLAH BLAH......... there is no end to learning , it goes on...so stop it ..just apply the knowledge what u have learned so far....

    5.circuit diagram:- 

     

     in the first section, ac 220v and 50 Hz is converted in to 12v and 40 kHz .u can also use frequency generator (usually available in all electrical labs) to achieve this purpose. 

    these transmitter coils is resonated with the receiver coil  where these ac current is converted into dc current by using bridge rectifiers and filter capacitors , to run  the dc load (here i used a dc fan (5v))

    6.how wireless better than wired????

    please give u r feed back...



    remote control

    Friday, 15 March 2013
    Posted by AVINASH CHAKRAVARTHI

    there are many way of communicating wireless
    IR (infrared):-
    • RF(radio frequency):-

      Here we will not concentrate much on how rf frequency works rather we will concentrate how we should use rf for controlling our robots by 4 or 6 or 8 channels.

      •  4 channel

       it means u can control four output or (2 motors with bi-direction)  
               main components required:-
     
    •     RF Module (Transmitter & Receiver)
       i have displayed 443 MHz which is usually preferred 

    •  circuit diagrams:- 

      transmitter ckt

       

      here pin 10,11,12,13 are connected to  the push buttons (inputs)

      receiver ckt:-

     here 10,11 12,13 were the outputs u need to connect the load are relays to switch into different circuit
    • if u are connecting  the relay to the output u need to follow the the  below ckt
     Explanation

    here the control is attached to the any of the output pin (10 or 11 or 12 or 13)
     when pin 10 in the encoder is pressed pin 10 in the decoder will be high so it switches the relay the output connected to the relay will be on
    •  if u want to control the motor bidirectional u need to follow below ckt 
    Explanation
      D0 connected to 10 and D1 connected to 11th pin of decoder
    if u pressed 10 and 11 in encoder the pins 10 and 11 in decoders will be high and motors rotates clockwise,
    if u pressed 10 alone  motor rotate anti clockwise,
    if u pressed 11 alone motor stop rotating.
    • 8 bit channel:-

      it means u can control 8 motors or 4 motors(bi directional)

       
      • components required
          ht 640 (encoder)
          ht 648l (decoder)
          RF Module (Transmitter & Receiver)
    • circuit diagram:-

      transmitter:-



      reciever ckt :-

       



      (  i'm sorry to  inform u the above mentioned ic's are rarely available in India as it was banned by Indian govt due to some unspecified reasons.)


    chassis types

    Posted by AVINASH CHAKRAVARTHI
      
    ...................!!!!page will be update soon !!!@.................

    Cloud Computing

    Posted by AVINASH CHAKRAVARTHI

    Cloud Computing





     Nowadays, Cloud Computing is one of the trending technology and it is becoming an essential part for the corporate world. Many companies are shifting from their traditional way to Cloud computing . In this article I will answer some simple questions about Cloud computing  i.e. "Why Cloud Computing?", "What is Cloud Computing ?", "How Cloud Computing works ?". In the End is the list of Top 10 service provider of Cloud computing of 2012.








    Why Cloud Computing ?

    This technology allows business to reduce IT operational costs by simply maintaining software and outsourcing hardware resources.

    Cloud is an optimal option when it comes to data sharing, that is why is use in industries is increasing on the fast pace.
     
    1. It bring down the IT operational cost. Reduced cost of work which means GOOD FOR BUSINESS. Hence Cloud computing making its day under the Sun.

    2. Cloud computing provides much greater freedom to share and use the data. As data is present over the internet a user can it anytime and anywhere by using any device (like mobile, tablet, computer etc). Since it require basic hardware structure so the cost of hardware is also reduced.

    3. As in business Time is Money, using Cloud computing there is not downtime there is only installation of one application for doing all the work. Hence it maintains everyone in organization on the same page and reduce the time to update and installation of different software for different application, hence reduce maintenance price.


    4. Security is most concerned issue in industries, which why usage of Cloud computing is increasing at the good rate because it provide more security than scattered network.

    5.Ease of Access and Ease of Use, both the things are loved by the industries and clouds provides these in very organized way that why clouds are working.
     So many benefits and only few downsides, so Cloud Computing is a good choice for IT operations.




    What is Cloud computing ?

    According to the name "Cloud computing ", ' Cloud ' specify the representation of the complex network as a Cloud in the system network diagram and ' Computing ' simply suggest that the art of doing some work, mainly with computers.
    All work is done by Web based service. Cloud computing run through Interface software. The Third party servers holds all the information software, your saved data and most important security.



    How it Works ?

    Cloud computing setup can be describes as two ends "Front end" and "Back end".  Front end is the user or the IT organization which have the Interface software like custom programs, word processing, etc,  and their licenses. Back end is the other end which is cloud provider.It is the network application servers and database storage. These cloud provider have all the hardware having capability of doing any work of any kind of application required by the user.


    Concerns of the Cloud computing

    1. User does not physically have the data with them, everything on the cloud.
    2. Risk of hacking of the Storage.
    3. All work become reliable on the Internet speed.
    4. More Knowledge is required for implementing and managing clouds.



    List of top 10 Cloud computing providers of 2012


    10. VMware
    9. Microsoft
    8. Bluelock
    7. Citrix
    6. Joyent
    5. Terremark/ Verizon
    4. Salesforce.com
    3. CenturyLink / Savvis
    2. Rackspace
    1. Amazon web services

    Amazon web services is on the Top of the all the service providers this year. It is the dominant public provider of the cloud worldwid
    •    Body's electric near-field confirms user ID

    • Microchip has developed a capacitive contact less identification system that relies on near-field effects around the human body.
      A $1 fob or token, carried about a person, sets up a field that extends to the wearers fingertips, allowing them to prove they are the carrier by reaching their hand towards a reader.
      AdTech Ad
      Branded Body Com, no license fees are payable providing it is implemented with the firm's chips.
      "This is not NFC, which is magnetic near-field communications. It is based more on the e-field. We use conductive pads which form a capacitor," Microchip business development manager Lucio Di Jasio told Electronics Weekly. "The idea is just to carry a Body Com token. You don't have to push a button. It can be in a shoe, a helmet, a purse or a pocket."


       The aim of the development was to transfer a few bytes of identification data with cheap components, with as much cost as possible transferred from the tokens.
      As such, the token has only an 8bit micro controller (a PIC16LF1827 in the evaluation circuit), an RF receiver, and an RF power amplifier (a CMOS inverter) feeding a flat plate aerial through an LC filter. One flat plate on each side of the token means that either can face the body, while the other couples to earth.
      The micro amp supply current RF receiver chip is an existing Microchip design: the MCP2035/2030 range originally developed for passive keyless car entry systems. Input sensitivity is 1mVp-p and modulation down to 8% can be detected.
      "Token battery life is 2-3 years," said Di Jasio. "The system has been in use in Microchip's Milan office for two years."
      As the receiver chip is optimised for operation around 125kHz, this has become the de facto frequency for basestation to token communications.
      Token to basestation communication is at 8MHz, chosen, according to Di Jasio, because it is the clock frequency generated by the RC clock oscillator built into many PICs. The RC oscillator is sufficiently stable for the system, he added.
      The receiver uses a PIC16LF1829 in the demonstrator, with a mixer taking the 8MHz to around 125kHz for a 2035 to provide amplification there as well.
      "A basestation cost can be as low as $2, said Di Jasio.
      The firm has chosen it existing KeeLoq protocol for identity confirmation.
      Around the body, "electromagnetic fields are 80dB below minimum allowed by the FCC", said Di Jasio.
      Using a 5x5cm flat plate basestation antenna, the hand of a person will pick up sufficient energy to wake their token at 15cm range, said De Jasio, and to complete the identification transaction at 2cm.
      "2cm is deliberately short for security. It is a trade-off between security and convenience," he said.
      There is a development kit (DM160213), an application note, and V1.0 of the development framework can be downloaded.
      "If you follow our framework specification, we have the patents and you need no other intellectual property," said Di Jasio. 
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