IR Tx and Rx : Big problem in a small project

Discussion in 'The Projects Forum' started by manikant, Nov 17, 2015.

  1. manikant

    Thread Starter New Member

    Nov 17, 2015
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    Hi,
    I am making a simple IR remote controlled switch using TSOP at receiver end and a 555 timer to generate 38khz signal at transmitter. The problem I am facing is that the output at TSOP is fluctuating continuously in the presence of fluorescent lamp or daylight.
    So can anyone suggest me any solution to remove this noise without modulation because there is only one switch to be controlled and modulation will make this simple task more complex.
    Also adding any filter won't be helpful because TSOP already contains filter.
    Also you can suggest me any small encode decoder IC for this purpose which can serve the purpose without increasing the cost much.

    Thanks
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Let's see your schematic. Is this the IR receiver you are talking about?

    The receiver should not be triggering in daylight, so this should be fixable.
     
  3. manikant

    Thread Starter New Member

    Nov 17, 2015
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    0
    No, my schematic is similar to the circuit discussed on this link http://www.circuitsgallery.com/2013/09/ir-remote-control-circuit.html.
    It is using a timer circuit to generate a 38khz pulse and a TSOP to detect that. There was no noise in daylight it was actually the fluorescent lamps that are causing the false triggering at TSOP i.e without using transmitter I am getting random outputs at TSOP.
    Pl help me out!!
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The BC557 Transistor is backwards in this schematic. The emitter should be connected to the positive rail and collector to the resistor that limits current to the LED.

    [​IMG]
     
  5. manikant

    Thread Starter New Member

    Nov 17, 2015
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    Yeah, its true. But still I am facing the same problem. I am getting noise signals at the output terminal of the TSOP. So it should be removed first before feeding it into the switch(transistor).
    Actually the problem is that the fluorescent lamp also emits radiations in the frequency range of 38 kHz. This is causing the interference .
    So please tell me if there are any other techniques other than modulation to prevent this interference.
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You need to add a small shade to protect the TSOP from the fluorescent light. The fluorescent lights use high frequency electronic ballasts in the 20-60kHz range. If you are unlucky enough to have
    - a light running 38kHz ballast
    - a cheap TSOP that does not have a sharp cut-off filter, or
    - a TSOP with automatic gain control (and gain turns up until the fluorescent lamp signal is significant)

    Then the only answer is a physical shade to protect from the fluorescent light. A small piece of black tubing or a small turn of black electrical tape around the TSOP should help a lot.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    Can't the sensor also pick up noise that is not light? In other words, these things are often shielded inside a metal box.
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Possible but the TsOPs have a pretty stout output. I guess the interference could come if there is no power supply decoupling capacitors and the OP put a megOhm size resistor between the TSOP output and his arduino. A bad connection is also possible.
     
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