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  1. M

    plz help urgently

    Hi audioguru is RIGHT the IC is quad opamp sarma ps thanks audioguru
  2. M

    plz help urgently

    Hi please see any datashhet for LM324 it an ic with four similar circuits called comparator. each one can compare two input signals and out put a +ve voltage or a near earth depending on the comaprision. this just in plain english approximately. for datails see the datasheet  at sl No 12 at...
  3. M

    Need to design a filter to allow only voice frequencies

    Hi perhaps the attenuation out side the audio band  depends on the % tolerence of the components you use across the filter like the one suggested by Audioguru Try toassmble one and  run a test with a set of frequencies,say , from 200Hz to 4 or 5KHz  and tabulate you will know the filter...
  4. M

    Resonator datasheet needed

    hi Hotwaterwizard SO NICE A Resonator like to see it in 4th dimension--(i mean some one performing on it sarma
  5. M

    Motorola's circuit doesn't work.

    hi Mic3ca whynot keep diode series to the resistor while reducing the 100k to say 1k as it is for base current limiting and the series diode can effectively block the -ve signal from RS232. ofcourse you could terminate the base with say 100K sarma
  6. M

    emitter turn off thyristor

    Hi rshafi68 pl try this PDF http://www.lib.ncsu.edu/theses/available/etd-08142006-235205/unrestricted/etd.pdf
  7. M

    Neutral , ground & earth

    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...
  8. M

    Need to design a filter to allow only voice frequencies

    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...
  9. M

    Pc Resets after a while. Where to look for the Probelm?

    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...
  10. M

    TDA 7088T

    hi Navinbabu take the datasheet you wanted attached here in future you may also try at www.alldatasheet.com TDA7088T.pdf
  11. M

    Pc Resets after a while. Where to look for the Probelm?

    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
  12. M

    DIODE QUERY

    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...
  13. M

    50Hz when you touch Oscilloscope probe

    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
  14. M

    Input Jack disables internal sound

    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...
  15. M

    DIODE QUERY

    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
  16. M

    4 Cellphone chargers into 1?

    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
  17. M

    BEL187 NPN Transistor

    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...
  18. M

    DIODE QUERY

    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...
  19. M

    AM Tuning Diodes

    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
  20. M

    efficient 12v to 5v regulator chip.

    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...
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