HELP ON IR...

Discussion in 'The Projects Forum' started by reymund, Oct 1, 2008.

  1. reymund

    Thread Starter Member

    Sep 23, 2008
    23
    0
    good day sir!

    1).I am now currently doing a simple project about transmitting and recieving ir wavelengths. i just want to know from the knowledgable ones on how to transmit an ir signal with its corresponding signal frequency.for example if i transmit a 4kHz freuquency of ir signal how can i detect the same frequency using a receiver circuit.

    2).If i use a 555 timer to generate the transmitter frequency is there any circuit configuration that would process the receiving signal from the transmitter?

    3).Another questions sir is that if the desired ciruits is achieved with their corresponding signal frequency allocation is there any possibilities that the receiver will activate if i uses another transmitter with different frequency? because during my experimentations i have an ir receiver or the phototransistor i use 2 different remote controllers from our tv and dvd player and it activates the receiver what i want to know is that is it possible to have frequency allocations on IR spectrum..

    thank you sir....
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Can you post the schematic of your existing design so that we can establish a starting point for this discussion?

    hgmjr
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Remotes work with a 38 KHz signal. The infra red is not modulated, just the on and off times of the signal (pulse code modulation). As long as the modulation is significantly under the frequency of the IR emission, the IR diode can be modulated at that or those frequencies.

    The recieiver is going to be a phototransistor. It will simply turn on and off with the received IR pulses. Any discrimination will have to be done with a passband filter. As the modulation just about needs to be PCM, it might be a challenge to do a dual modulation with no cross-talk.
     
  4. reymund

    Thread Starter Member

    Sep 23, 2008
    23
    0
    sir apparently for now i dont have the schematic and i am working on it based on the theories related..

    sir basically on the transmitter panel it compose of 555 timer astable type and the ir diode is connected to the outpout termnal...

    and for now i am trying to create a receiver that corresponds to the transimitter signal it is compose of either inverting or non inverting amp confiuration for now im not sure what im going to use..

    i am still open for the others suggestions thank you sir.
     
  5. reymund

    Thread Starter Member

    Sep 23, 2008
    23
    0
    to beenthere sir what do you mean by this???...

    "Any discrimination will have to be done with a passband filter."


    what will i doowith the pass band circuitry???...
     
  6. veritas

    Active Member

    Feb 7, 2008
    167
    0
    You would use a band-pass filter to detect a given frequency range.

    What he means is that your photoreceiver will not be able to detect the frequency of signal you are sending it.
     
  7. reymund

    Thread Starter Member

    Sep 23, 2008
    23
    0
    sir if i uses the pass band circuit on my reciever side, is there any frequency to be designated on my transmitter???

    thanks for the info sir!..
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The transmit frequency should be in the center of the filter's passband.
     
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