RF transmitter using saw resonator

Discussion in 'The Projects Forum' started by yogeshk, Jul 2, 2014.

Saw resonator RF transmitter design

Poll closed Jul 7, 2014.
  1. RF transmitter design

    1 vote(s)
    100.0%
  2. Saw resonator based design of RF transmitter

    0 vote(s)
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  1. yogeshk

    Thread Starter New Member

    May 29, 2014
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    I am trying to design a small low power RF transmitter using a saw resonator.
    My circuit is somewhat similar to the circuit given in the link except for the R3 resistor.
    The saw resonator I am using is 433 Mhz and the frequency of the tuned circuit I calculated comes out to be 443Mhz. Does this makes a Difference.
    The RF transistor I am using is BFS17A and the values of the components areas below.
    C1=5pF , C2=18pF ,L1=33nH, R1=47K, R2=100 and RF bypass cap =470 pf.

    But the circuit is working only for a small distance say 1 meter. I want to make it work at around 10 -20m.
    I am using a general purpose PCB for the same with DIP components.
    Are there any solutions to this.
    I am using a pair of Encoder and decoder. Please provide some solutions .

    [​IMG]
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    You forgot the link to the circuit.
    What is your antenna for transmitting, for receiving?
     
  3. yogeshk

    Thread Starter New Member

    May 29, 2014
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    0
    The circuit is given in the image I have inserted and the inductor is acting as my antenna.
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    I cannot see any image?
     
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
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    couple to an antenna, your range will be better than just an unshielded inductor.
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    couple to an antenna, the range will be better.
     
    Last edited: Jul 2, 2014
  7. DickCappels

    Moderator

    Aug 21, 2008
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    Can you post a link to your image? I can't see it either.
     
  8. bertus

    Administrator

    Apr 5, 2008
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  9. alfacliff

    Well-Known Member

    Dec 13, 2013
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    at 433 mhz, coils are so small they make real bad antennas. add an antenna.
     
  10. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Thanks, bertus. He must mean this image, you say?

    [​IMG]
     
  11. yogeshk

    Thread Starter New Member

    May 29, 2014
    3
    0
    Yeah I mean the same image as shown by Bertus. But what about the resonant frequency of my tuned circuit, it should be close to 433Mhz whereas it is 443Mhz.Does this makes a difference. Can anyone please suggest some circuit with components values.
     
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