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mvs sarma

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Everything posted by mvs sarma

  1. Hi rshafi68 pl try this PDF http://www.lib.ncsu.edu/theses/available/etd-08142006-235205/unrestricted/etd.pdf
  2. Hi electrosimonics to best of what i could recollect NEUTRAL is used for public mains supply, either single phase (Live & neutral) or three phase Star connection ,4th wire being neutral. the concerned electrical supply companies general connect the neutral to ground at the point of thier distribution stepdown Transformer' output. It need not essentially be at earth potential by the time it reaches the user premises, but will be near to ground Ground and earth are similar words-- i saw the term ground being used in American documentation especially. sarma
  3. hi sundar_milo A filter alone cont, i fear, identify whether it is voice. it can only decide whether the frequencies are within the so called voice band(as per the term generally used in telecom .3 to 3.4 KHz and in some countires .3 to 3 KHz) now if the signal contains signals like music tones like DTMF within the pass band of these filters they sicerely allow. the characteristic feature of voice is that it is not continuous and there are define breaks. perhaps your algorithm should also check for this. sarma
  4. Hai Shahriar overvoltage__ Input-- you have a very large window for input voltage. perhaps you may use an UPS like APC at the input and it has built-in stabilization. output - alrady design looks after. it is some times seen that there are some ZENORS ACROSS THE OUTPUT VOLTAGES SO THAT IN CASE OF FAILURE OF CONTROL LOOP, THE zENOR LIMITS-- BUT HOW AND HOW LONG -- A QUESTION MARK. SARMA
  5. hi Navinbabu take the datasheet you wanted attached here in future you may also try at www.alldatasheet.com TDA7088T.pdf
  6. hai shahriar generally components with high current might cause dry solders . first check these. In smps you find that the elctrolytic caps give way by drying up after some time if you coud replace as a set the smps should work. also see that the Fan in the smps is up and running. sarma
  7. hai prateeksikka plese think about your qestion. is the diode a part any circuit or it is stand alone with no connections. does yuor doubt belong to any specific circuit? if so which one. what charge on the diode you are talking about ?? ALL Qs only is it not ? please moderate your question to be able to get a reply. sarma
  8. you are right aartak. it is a good paractice to earth ant test equipment before it is used. the problem wont be there and it cultivate a healthy habbit. Nice sarma
  9. Welcome to the fourm As you rightly described, the aux input jack cuts the Radio detected Audio and extends the audio amp input to the externally connected cable. It is a mechnical disconnection as you plug the external input. why not you try to indicated thr model and brand name and if possible the IC used for the radio abd audio if seperate. this wold help in proper improvization-- sarma
  10. FINE MP i am reminded of FOOL or JOKE circuits that used to apper in the Summer circuits edition of ELEKTOR magazine (NL based) there aslo we used to find one or two absurd circuits and an almost convincing write-up even-- i agree we need some lighter coner to relx sarma
  11. these li-on chargers will have their own control circurty with input voltage being common, say at 5.1v dc, however if it isdesirable to have isolation you may have adiode in +ve lead of each output with a electrolytic filter cap of suitable value. sarma
  12. audioguru BEL187 is a low voltage power NPN tranasister manufactured by Bharat electronics Limited (BEL) in India. you may compare it as a silicon equivalent of AC187 made earlier. it is to92 package but with small heat sink. this device with its complimetary BEL 188(PNP) is used as a power out put of audio in portable radio and other applications. perhaps sl100 with complimentary sk100 can be used, the space to be bargained. sarma
  13. MP, how came to such conclusion? the circmustances to be elaborated where from smoke comes? 1. yes if the diode is in the shunt path like that in an smps with forward mode -- 2. a. yes if one diode of a bridge is shoted-- b. if the diode of anhalf wave rectifier type adopter is shorted, the electrolytic filter cap blows due to -ve half cycles. sarma
  14. hai Taxx, try for free or paid samples KDV149 from korea electronics company the datasheet is at alldatasheet.com and your selection was fine sarma
  15. if you can accomodate more parts go for MC34063C, the datasheet you may study. of late there are 4 pin swichable regulators providing for economical space saving and efficent ones. perhaps nationa semi has few of them. for all linear methods you will have to loose energy acroos the set up. sarma
  16. here goes a pdf of ceramic resonators sarma ceralock.pdf
  17. please try IRFZ44 intead of ON resistance of 12 m ohms it may be 28 M ohms device can work upto 60v and Id od of 50 amps It is generally available sarma
  18. TRY THIS SITE prst-ab.aps.org/pdf/PRSTAB/v9/i8/e083501 picked up at http://www.google.co.in/search?q=PREVENT+SILVER+FROM+OXIDATION+WHILE+SOLDERING&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-GB:official_s&start=40&sa=N sarma
  19. i agree with MP as i had experienced situations when i go for search, it refers back to ELECTRONICS LAB. HATS OFF TO OUR WEBSITE & ITS CONTRIBUTERS. HAVING SAID THAT, i personally feel that a student, hobbyist, old fellow like me dervie encouragement equally when we see that there is a force of international community chating with you,guding you, warning you aganist possible mistakes and loss of money by purchaing overspecified costly parts, what not?? this msite has been rendering a good practicable supprot. WORTH CALLING A TELE-LAB. SARMA
  20. hai audio guru, while in line with your concept, you may perhaps agree that the power line, even though on the same pcb, is likely to have large variations as the load increases and it would be safe to have filtered , rather condtioned supply for the CD4047B, pl comment sarma
  21. It has been a practice to keep emmiter resistors to limit th current under failures before a fuse could blow. i suggest few more additions. 1. an electrolytic cap of considerable value proportion to the load crt across the +ve and -ve very near to the transformer mid point and common ground of the O/p emitters . also it is better to add a series resistor of low value and an electrolytic to act as a filter while feeding power to the CMOS IC. one point is not clear how the device cd4047b is adopted for such large power supply, while a serios thought is to be given to dead zone ( a small time lag between return to zero of the plulse on Q output and raise of pulse on Q* output. let us recollect that lack of this deadzone would bring bottom pair of transistors on before the current in top ser dies down. modern ICs like sg3524 have taken care of this phenominun while working at high frequencies and few manufacturers adopt 3524 at 50 Hz output . perhaps someone can enlighten me further. sarma
  22. this problem is prevelent even with 74 series . a cct rigged up on a prototype had misarably failed due to noice pick-up. perhaps with proper precautions towards poer decoupling at each IC and by keeping poer extention boards, etc away from the project prototype, and by sticking the specific metal sheet supplied with the bread board, beneath and keeping at earth potential, we may suceed in preventing the power pickup problems. all of us are aware of antisattic wrist straps with earthing cwire etc . these are to be specifically used when working CMOS digital ICs and in locations of low relative humidity. ( B series, now a days are ruggedized by protection diodes across every pin to prevent failure, induction is stil a problem) . whether one measures 50/60Hz or a hormonic depends perhaps on the amount of induction and amount of noice generated by devices adopting triac conrollers- even after all the reglations reg power purity. hope with adequate precautions one could still prototype and test on bredboards. anxious to track the success of test rig ups. sarma
  23. ESR stands for equivalent series resistance of an eleco. no componenet being ideal, the elec caps used for filtering the output shold be of low ESR and such caps are being supplied as esr caps. you may search for addl data on the subject www.e-sonic.com/whatsnew/emag2004_3/emag_Passive_nic.pdf sarma
  24. it is almost 7Mb and i fear the only way is to download for oneself as there wold be restriction on size of of attachement please try at http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1434 sarma
  25. good nyjumpee, it calls for 2.6 amps if all the items are to be charged same time you will perhaps have problem once the sigle proposed charges goes faulty--- redundancy would be better you may try to develop a psu with 5.0 output and a current capacity of atleast 3 amps -- may be LM317 with a pass transistor for current boost. Set it for 5V and locally rig up a multiway usb sockets and wire them with only +5 and return wirs at the appropriate pins-- logically it should work-- how ever i agian suggest , think interms of redundancy sarma
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