help me pick an IR receiver

Discussion in 'General Electronics Chat' started by bug13, Sep 27, 2013.

  1. bug13

    Thread Starter Well-Known Member

    Feb 13, 2012
    1,208
    38
    Hi guys

    I am working on a proximity sensor with IR Led and IR receiver, it needs to detect a hand or other object in about 75mm.

    First I use this TSOP6238TR, it all work well except that it pick up the signal all the time in dark, due to the auto gain control in the chip, it has a very high gain in the dark, it can pick up signal relect from other object far away.

    So I replaced it with this TSOP5038TT, this one work fine in the dark, but it will pick up the signal from my engery saving light bulb all the time, so my normal signal is swampped by the signal from my energy saving light bulb.

    So what kind of IR receiver do I need to be able to work in the dark, and doesn't effect by energy saving light bulb?

    Carry frequency is not so important as I can change the code in software, as long as it's do-able with a 8bit timer and 1MHz clock.

    Thanks guys
     
  2. IC-Man

    New Member

    Jan 3, 2012
    26
    4
    Hi bug13,

    Maybe you can work at a higher frequency. Like the iC-LQNP from iC-Haus uses a bandpass filter at 144khz and has also ambient light supression: DS link http://ichaus.biz/product/iC-LQNP .

    Take care
     
  3. bug13

    Thread Starter Well-Known Member

    Feb 13, 2012
    1,208
    38
    Oops, I forget that I am limited to the frequency of the IR receiver that are usually available in the market.

    Or other solution to my problem, it doesn't have to be finding another IR receiver.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    You have the wrong type of I.R. sensor for that task. Using a "smart" sensor is no good as it will self-adjust its gain which will pick up noise (like your light bulb) and also wrecks any ability to set a distance.

    You need a plain IR photodiode, and you can adjust its gain with a trimpot in the circuit to set the sense distance. You also need to modulate the IR LED, and have an AC detector on the IR photodiode to detect only that LED signal and no other IR AC signal.

    The circuit will get complex and still have limited accuracy.

    It's better to go with a complete IR proximity sensor like the Sharp GP2xxxxx sensors, these use triangulation to give accurate sense distances even with chnages in ambient light and surface colour.

    You can get the Sharp GP2 sensors for about $10, which is very cheap since you don't need to buy LED, photodiode and all that modulate/demodulate circuitry.
     
  5. bug13

    Thread Starter Well-Known Member

    Feb 13, 2012
    1,208
    38
    This sensor is a bit on the expensive for my project, but good to know that there are these Sharp GP2 sensors are available. :)
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    That $10 is a hobby store price for singles. I have not checked bulk prices but they must get a lot cheaper in quantity from wholesale suppliers. :)
     
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