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  1. Ramji1

    Discrete PLL design

    Hi all,             Im trying to implement a discrete phase locked loop circuit(PLL). I know the basic functioning of the PLL and its different parts and i have used it as an IC. But I want to implement a discrete PLL circuit using separate components for Phase Detector, Loop filter, VCO etc...
  2. Ramji1

    IR Headphones

    Because of lack of time i havent been able to design a FM circuit for this.. Instead i have stuck to the AM circuit which i have sent earlier in the file "irfm.pdf" The circuit workd perfectly for me once i modified the transmitter. I replaced the amplifying stage into a 2-stage common emitter...
  3. Ramji1

    IR Headphones

    ok... I'l hv to read about VCOs n PLL's n then construct the circuit myself. But assumin that i produce a FM audio signal. How do i transmit and receive using IR? Do i use the same LED n photo transistor mechanism?(Isnt that AM then?) Or do u suggest a different mode of transmission??
  4. Ramji1

    IR Headphones

    And one more thing. The schematics for FM transmitters of radios are easily available. Can i use those schematics to produce a FM audio signal and then try to transmit using infrared? Again its the transmission part that i dont kno much. How do i transmit such an FM signal thro possibly IR...
  5. Ramji1

    IR Headphones

    Yes the music IC does bias the transistor i think. And it'l cause distortion. How about giving a bias DC current to the transistor to prevent it? Will it minimise distortion? How much of a current do u reckon wud be enuf? And the red LED simply acts as an indicator. So it can be removed and...
  6. Ramji1

    IR Headphones

    Ya even i hvnt got the FM circuit. But i found that a similar AM IR transmitter has figured in the Jan 2007 edition of EFY magazine. I hv sent the schematic along. It transmits a musical signal thro IR and i suspect it uses AM too. Just hv a look n see if this is a workin design. I kno its...
  7. Ramji1

    IR Headphones

    Hi audioguru,   Thanks for the info. And i get most of wat u meant. I dint know bout AM or FM in IR transmission. Anyway i think i'l drop this circuit and go for a FM design. So can u help me Find a schematic for FM transmission using IR. And also i hv some clarifications regardin some of the...
  8. Ramji1

    IR Headphones

    Hi all,         I hv gotta schematic to build a IR headphone set. It simply amplifies the audio output signal from a TV or Computer and transmits through IR Led's. This IR signal is received and given to the head phones wher the original sound can be reproduced. Im plannin to do this as a proj...
  9. Ramji1

    Please help on "Telephone voltage levels".

    hey the idea is pretty cool... It wud even help me regardin a telephone proj that i hv plannd on.. Can any1 get me the internal circuitry of the telephone...
  10. Ramji1

    pnp vs npn?

    Hi indulis,       Actualy i hv come acros fet's, mosfets etc.. i mean i knw their functionin structure, characteristics etc. But im nt able to figure wts the advantage of a NPN over an PNP transistor. The only benefit i find is that in NPN the base current adds to the output collector current...
  11. Ramji1

    pnp vs npn?

    In my short exp of electronics fr the last one year i hv come across mostly only NPN transistors. Is there any particular advantage of an NPN transistor which makes it more favored in circuit design than PNP transistors??
  12. Ramji1

    What are Heat Sinks??

    Hi ante,             What exactly do u mean by "compound"? I understand that the transistor must be mounted on the heat sink through an insulator(should it necessarily be an insulator??) having high thermal conductivity. And what r the benefits u get from using mica or "compound"?
  13. Ramji1

    What are Heat Sinks??

    Thanks fr ur responses. I understand the general outline of a heat-sink and how it works. Now i am keen to see the real device. I'l just browse through some sites and get back to u guys if i have any more doubts.
  14. Ramji1

    What are Heat Sinks??

    Yes i get what u mean in theory but i want to know its application in electronics. To be frank i dont know how a heat sink wil actualy look. Is it somthing external that u connect to a transistor or does it come built-in to the transistor? Can u help me with some diagrams or pictures? I myself...
  15. Ramji1

    What are Heat Sinks??

    Hi all, Im a starter in Electronics as well as starter in this forum. I have learnt somthings about heat sinks and how they limit the heating up of transistors. But im not able to grasp it fully. Can anyone provide me with any explanation or notes on heat sinks preferably with some diagrams and...
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