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433MHz rf module interfacing problem.. plz help

Discussion in '8051/8951' started by bobparihar, Sep 26, 2014.

  1. bobparihar

    bobparihar New Member

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    I am using a circuitry to send data through wireless.. using RF of frequency 433Mhz
    my circuit is as follows
    the problem here is that this works but the range is only 2m
    i had also attach a wire antenna of about 5cm to both the transmitting and receiving module.. but it does not work
     

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  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Have you checked the datasheets for the Tx and Rx modules to identify the best antenna configuration?
     
  3. bobparihar

    bobparihar New Member

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    iam somewhat confused here.. here in my circuit diagram it uses 750k ohm between the pin n0. 3 and 4 of encoder for oscillator and 27 k ohm at the decoder end..
    but in some tutorials i have seen 1M ohm at the encoder and 33K ohm at the decoder..
    well i have seen what iam doing in many tutorial too..
    can some one explain this? does iam doing somthing wrong?
     
  4. dave

    Dave New Member

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  5. alec_t

    alec_t Well-Known Member Most Helpful Member

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    :confused: Your diagram shows the resistors between pins 15 and 16. Are you sure you have the ICs correctly orientated?
    I don't think the values are critical.
     
  6. bobparihar

    bobparihar New Member

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    i have seen in some tutorial the resistance is of 1M ohm at encoder side and a 33k ohm at the decoder side..
    i hav also seen 750k ohm at the encoder side and a 27k ohm at the decoder side in some other tutorials...

    but i did experimented both and both works..
    but the problem is with range
     
  7. alec_t

    alec_t Well-Known Member Most Helpful Member

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    That's what I would have expected.
    Re-read post #2. Short monopoles/dipoles are inefficient.
     
  8. jjw

    jjw Member

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    You could try higher supply voltage for the transmitter and l/4 antenna ( - 17cm) in both transmitter and receiver.
     
  9. atif123

    atif123 Member

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    use this circuit
     

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