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Posts posted by shekhar_dandya

  1. Hi All,
    I was planning to build such an F.M transmitter and got a lot of important information through the threads.thanx EL :).

    Actually I was planning to connect such a transmitter to speaker output of my computer so that I can hear MP3 and other music from my computer on my radio FM band.
    I think it would require an impedence matching stage at the i/p.but what x'tor configuration to use that has a low i/p impedence(8 ohms) and a high o/p impedence(in kohms)?

    The second thing is how do you decide the range of x'mission?

  2. Thanx Ante.This was nice one to statr with.But I need still more understanding of the basics.I searched on google but did not find a satisfying article.
    need more help
    especially how it is used for FM detection etc,tone decoding..

  3. Hi Everyone,
    This was the question asked to one of my collegue in interview:
    Data is comming on a serial line at 1Mbps.I want to delay this data by 1 sec .How do I acomplish it?
    Using shift register with a 1Mhz clock and 1 million+1 D flip flops.
    This is my answer.
    Is there any more elegant solution?

  4. Hi AudioGuru,
    Thanks for the soldering tips.I did not make a PCB for my circuit.I just used a general purpose board that provides only mechanical stability to components and soldering pads to adhere the components to the board.
    As far as your high power X'mitter speculation goes,I have our city 's TV transmitter as well as our local radio's FM X'mitter nearby i.e about 50-60 km away.Could that distance be a problem?
    Well the big prob is I don't have a CRO to watch the effect.

    Anyway if you say that this isn't going to cause any problem to power small electronic circuits (cordless phones,radios/tapes etc)I will leave the problem as it is.

    Thanks all of you for your cooperation and patiently replying my silly questions.

  5. Hi Kevin,
    I am using a TO 220 package and have connected pins properly.
    I have no problems with d.c.
    How does 317 ener voltage follower mode ?
    I have used a 240 ohm resistor from o/p tp adj and a 330ohm in series with a pot of 4.2K from adj to ground.I have also pput a 10uF cap at the o/p to reduce the ripple.
    Can I just neglect this thing happening for practical applications?
    I heard that people making adapters(ac-dc converters) do not bother to use a regulator as well.
    Am I expecting too much from my cheap circuit?
    more help needed.

  6. Hi everyone,
    Well I did not require to use caps to earth for secondary.Its not showing any dc voltage now.But at the o/p I still get 6V ac when dc o/p is 3V and 56V ac when dc o/p is 25V(both no load.).Also the conditions did not improove with a load of 330 ohm resistor as a load.
    when the DMM connections are reversed(i.e +ve lead to -ve of 317 and -ve lead to +ve of 317)I am still getting 0V.
    (Whereas I expect at least a -ve voltage).Can this be due to bad soldering? My soldering is horrible.I don't have a
    scanner to show you people.
    The dc voltage between o/p and adj pins is 1.25Vdc.When measured with DMM knob kept on ac it reads 2.2V.Again,with the DMM leads polarity reversed it reads 0V.
    The dc o/p at the i/p of 317 ie across the filter capacitor is 31Vdc.when measured with knob kept on ac it reads almost 68V.
    Again the same thing ,you reverse the connections and it reads 0V.

    Somewhere in the ongoing thread Suraj said :

    Check your multimeter. If you are measuring DC voltage on AC range some multimeters display double the Value (this was true with older analog ones).
    .COuld this be the case with DMM's?

    Help needed.
  7. Hi Guys again,
    This time I checked the o/p of my 317 by keeping the DMM knob on
    'AC -V'. WHen I connect positive of DMM to positive supply terminal and -ve to ground,I see 29V AC(RMS?).When I reverse the connections(+ve t o ground & -ve to +ve) my DMM shows 0V! what exactly is the nature of this voltage and why is it affecting?

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