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mvs sarma

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Everything posted by mvs sarma

  1. they are definitely capacitors metalysed Polyester type mostly used for decoupling or interstage coupling you may measure tha ctual vaue on any multimeter having capacitance range sarma
  2. please see the BTL aplifier application in the attached Philips Application note. the electrolytic cap on pin 3 is not shown in BTL application pl check also the input should be 1v line in equivalent for proper audio output as audioguru already suggested try pre setting the vol cont of the said MP3 player for proper input to the power amp. next to this , perhaps i fear whether the IC is OK or Not ? tda1519a.pdf
  3. please try url http://www.smps.com/PSpice/simulation.shtml in the bottom of page you get the locations for Pspice models sarma
  4. i am totally in line with audioguru's philosophy-- there were times when power was generally indicated (specified) as RMS watts. --over times the pmpo took over. in fact the transformer used in the multimedia speakers is too small( if not three small) it coud deliver few ma at 12V finally the output power could not be greater than 400 to 800 mW per channel as the input DC power is 1 watt max sarma
  5. hai u have just added an emitter follwer to the outputof 2nd Tx right. If so, perhaps you need connect the aerial at the emiter , just see. hope this should sort out the issue. hope to get a feedback sarma
  6. you may use 555 as oscillator and use one driver transistor like C1061 and use 6V/230V transformer [ if possible the core shall be repacked (All Es one side and all I s other side ], with a gaping paper placed between them and the whole Transformer repacked) to prevent saturation-- for oscillator you can also try cd4047b both in astable mode at say 40KHz. of course the component count will be more as compared to what you showed. Finally the CFL will not have filament drive and the CFL itself needs a modifivation in the sense that these CFLs come with a built in starters meant to work at 230v/115v AC with a suitable choke. this starter is to be replaced by acombination of 470K(0.25 W ) resister and 2n2 cap in parallel. many chinese make lanterns use HiTachi type 6" tube without filament pre-heating finally perhaps audioguru 's openion is right that the illumination may not be to the expectation?? you may however try it out sarma
  7. please download datasheet as sukhbider indexed in his message (reply#28)and you will find mono, stereo and even the tentative pcb layouts-- y-day iattended a mutimedia speakers using a similar version UTC2822 9V DC input) and is working fine -- you may rather GO AHEAD sarma
  8. you may well settle for an ic based amplifier instead of valve amplifier. it might save power and space both , unless you are specific of valves however you might need valves like EL 84 FOR OUTPUT POWER sarma
  9. 223 and 473 appear to be smd resistors as per the photo reg the ic marked BBHH let me try as the item is purcheased at Ebay the concerned add may indicate the manufacturer and perhaps a mail req the manufacturer may help for the service data with schematic and artwork or even the ebay may replace the item sarma
  11. mvs sarma

    FM Radio

    Fine-- there was a time lapse in my reverting back-- as i was out of station attending on a relation who was sick, thus not verymuch on net. i went thro all the letters and also the philips application note an192 PIn 5 of TDA7000 sits on =ve voltage thus the Varicap positioning is RIGHT the circuit is also checked working by andy815 with potentiometer. i stand corrected. sarma
  12. mvs sarma

    FM Radio

    hai all plsee carefully the FM radio schemtic of the project and you will appeciate that THE VARYICAP IS SHOWN CONNECTED WRONGLY-- IT SHOULD BE IN THE REVERSE DIRCTION TO THE BATTERY POLARITY, ON THEN, THE DIODE WOKS AS A VARYCAP PL TRY OUT YOU ARE SURE TO START RECEIVING STATIONS anxious to get feedback sarma
  13. dear sukhbinder pl try this URL from electronicsfor you http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/aug2005/CI-01_Aug05.pdf&title=Medium-Power%20FM%20Transmitter sarma
  14. please try www.cq-tv.com and download 1994 february issue (issue 165) you will find 24cm ATV Transmitter authored by Tim Forrester sarma
  15. with a little relaxation of area you may perhaps try ELECTRONICS FOR YOU monthly mag from INDIA . you will not be disappointed. look at www.electronicsforu.com all the best sarma
  16. dear audioguru, being a retired engr of telecom from india, i recollect that we were able to achieve a balance of say 40 db-- i do understand -- but i was only trying to think of a way loudly -- i do realise that we have to do a lot towards perfection. if something works and with a lot of zeel and patience it coud be possible -- how ever there are other straight forward and easier models of desogning -- one need not of course stick to a single speaker doing bothe the jobs -- ok thanks for the reply please sarma
  17. if it is aroud distinguhing between two cellponones ringing--RF has nperhpas less to do--all cdma or gsm technology-- setting a bit inyour phone makking it generate (simulate ringing)-- if it is only rquirement-- perhaps one could change the ring tones by selection and crate two different tones towards ring distingushing-- even if the request is centered around detecting signal from the air-- i fear one may not be able to use simple technics like filters detectors etc,, pardon me -- sarma
  18. i understand audioguru and thanks to Eurobuskers-- i really feel like realising it-- in telecom we have something called 4port hybrid-- ofcourse a pasive network. converting 4 wire to 2 wire -- if one can recall the principle involved there-- it is not a problem realising a speaker receiving signal from an adjecent port and the same working as a mike pumping into the adjecent ports as looked from the speaker-- let me analyze- call the four ports N, E, S, & W same as north,east etc now the recived output may be fed from west port -- it will be distributed to N&S but minmum (null if balanced) to E port. the speaker could be imagined on N port -- next when speaker ,working as a mic will output small signal from N port to equally distribute to E &W ports. the signal towards W is wasted --while the one towards E port could be amplified and with necessary feedback and still be used with minimum disturbance from in coming signal-- ofcourse it calls for careful balancing of the hybrid network-- detailed explanation could be found in transmission technology of telecom fundamentals-- these things are like challenges to youth and few of them do realise- the immposibles (so far so) all the best sarma
  19. as all of us know, in a linear power supply with such broad spec like 0-30v dc and current demand of 5 amps- lot of power is likely to be wasted- A) if the spec permits why not the rectified DC be processed thro a switcher and a non- isolated output is taken in a buck regulator form( as the mains transformer provides for the necessary isolation)-- of course taking care of ripple limits. B) whather thr primary could be controlled using anlectronic fan regulator (thyristor type) in series to primary, the secomdary rectified and adequate filtering done to suite the needs or C) procure a transformer with taps at say 9V (for 0 -6 vDC output ), 18V and full-- try switch teh limb to the rectifier-- out put configured to an adj regulator with series pass and the adjustable pot also switches symultaneously-- ganged switch. with one of these methods perhaps we can device and still try to save on power -- any comments welcome sarma
  20. please try this site http://www.datasheets.org.uk/specsheet.php?part=CS9021 similar for cs9018 also sarma
  21. Alun, if cost is not a creteria, i suggest , you limit the bandwidth to 3khz, and now you try to switch the active limb of the speaker, to Input / output at a faster rate(by some FET switches using an osc ( say 4066). ( i mean chopper) thus if the switch points spkr as out put you listen and whan as input the signal goes to ip of an amplifier. of course you may have to filter the osc frequency from the audio O/P . i accept it as a concept and i am sure you can take it ahead-- all the best-- i shall be happy to get feed back from you sarma
  22. look at url below http://www.alldatasheet.com/view.jsp?Searchword=R6C and all the best
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