Convert Wave sounds to IR signals

Discussion in 'The Projects Forum' started by MartinLarsson, Feb 25, 2009.

  1. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
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    I've recorded the IR signals from my TV-remote as a wave on my computer. And now I want to play them through an IR-diode, instead of the speakers, so I can control the TV from my computer.
    Now, the problem:
    It did not work to just connect the diode to the computer (no surprise) so I tried to amplify the signal with a transistor, but apparently it's not that simple.

    Do anyone know how to make a circuit that will make it work?

    The IR-diode is 1,2V and 100mA and the input voltage would preferably be 3V. Ohh and I am just using one of the stereo channels, so it should be mono...
    (I recorded it with PCM at 44,100 kHz and 16 bits.)

    Thanks!
     
    Last edited: Feb 25, 2009
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
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    Thanks but that was more complicated than I wanted. I just want to make the signal stronger (I think), without those IC-thingies... Ty anyway!
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    What samplerate did use for recording ?
    Most IR remote control signals are about 38 kHz.
    It can be that when you "playback" the signal it is totaly distorted.
    (a soundcard mostly has a highcut at 15 - 20 kHz).

    Greetings,
    Bertus
     
  5. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
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    I don't thinks it's the samplerate or any other quality setting. The sound is good I just can't send it though a transistor. When I connect the comp. output to Base and Emitter, and the power to the Collector through the transistor and then though the IR diode or any speaker/headphone. The signal disappear. Not a sound. Therefor noobish as I am (for a geek) I suppose that I've made the circuit wrong and want someone to make a working one for me (made of simple components...).
    Thanks, but I really need this to work!:)
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    The signal of 38 kHz can not be heard.
    I think you hear a signal that is downsampled.
    You will get something like this :

    [​IMG]

    The picture comes from this page:
    http://zone.ni.com/devzone/cda/tut/p/id/2709

    Can you draw a schematic of your transistor setup ?

    Greetings,
    Bertus
     
  7. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
    17
    0
    It's kinda like the one I have, or it is. But I have tested things like remove the resistor, connect the speaker (IR-diode) parallel with C and E and change the voltage and such.
    But I can hear the signal when connecting directly to the input but I want it through some kind of circuit so I am sure to get the right juice to the IR-diode.

    Time to hit the sack! THANKS!!!
     
    Last edited: Feb 25, 2009
  8. bertus

    Administrator

    Apr 5, 2008
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  9. davebee

    Well-Known Member

    Oct 22, 2008
    539
    46
    To amplify what others have previously said -

    The IR coded signal looks sort of like RS232 at a fairly slow data rate, so you will be able to hear it through an IR detector.

    BUT - when it is sent, it's pulses are ALSO chopped at a very fast rate, 38-40 kHz. The IR receiver is designed to reject any incoming signal that doesn't pulse at that fast rate.

    So even though you may hear sound due to the detected IR pulses, that's not enough to operate the receiver. The PC sound card may be able to record the slower pulse trains, but it may not be fast enough to either record the incoming 40 kHz signal OR send out a recorded 40 kHz signal.
     
  10. fish4fun

    New Member

    Feb 24, 2009
    8
    0
    Martin,

    I just want to clarify what the others are saying. Your sound card is not likely to prove viable as a signal source for an IR remote. Most IR remotes work by sending variable length pulse trains of a specific frequency, typically 35kHz to 40kHz. I have seen projects that use a com port or, even better, a parallel port to "make a remote". Sadly, all the ones I have seen are Linux or DOS based. I would assume someone has figured out how to bend windows to emulate a remote w/o a uController, but the task is MUCH easier with a uController.

    Here is a link to one such PC based IR remote:

    http://www.armory.com/~spcecdt/remote/

    In the end, unless you really want to spend a lot of time on this, you might consider something like this:

    http://www.usbuirt.com/

    I don't know anything about the above device other than it came up first in a google search and claims to do exactly what you want.

    Good Luck!

    Fish
     
  11. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Your transistor circuit has many errors causing it not to work.
     
  12. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
    17
    0
    Well, thanks everybody anyway:)! However, if someone makes it work or w/e I have a nice program made in C# that will by speech recognition change channel. Just so you know... :D

    Thanks!
     
  13. MartinLarsson

    Thread Starter Member

    Feb 25, 2009
    17
    0
    Would this work or could you be more specific on what's wrong? I have read many different documentations on amplifiers and such but I don't get it... :confused:
     
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