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Thread: 38KHz Ir detector counter issue

  1. #1

    Unhappy 38KHz Ir detector counter issue

    Hi all,

    I have got a 38KHz Ir receiver which appears to be working properly. When I connect it to an LED, the LED blinks as I blink the 38kHz source Ir source. But when I try to count the number of times the output has changed from low to high, or high to low using the microcontroller, It counts up, even when the source hasn't changed state. I have been at it for a while.

    Any help would be much appreciated.

    Cheers,
    Ankit

  2. #2

    Default

    I don't come to the forum regularly and have only just seen your post even though it's more than a month old. Have you solved the problem?

    Your problem may be due to interference from other sources. Incandescent light bulbs, tube lights, sunlight, etc can cause false irregular output pulses from the IR receiver. I solve the problem by wrapping the receiver module, except the sensitive part, with sticky aluminium foil. Things like electrical insulation tape are not suitable because they are not completely opaque.

    On a module like the TSOP1738, the sensitive part is at the top of the front bulge. You can further reduce interference by placing a small tube in front of the sensor. I used this technique in a recent project and can use my IR Tx-Rx system in bright sunlight at a distance of more than 25 feet between the two.

  3. #3

    Default

    Try all that Pimpom has suggested. Also try this.... Whenever you read a change in the input just give a delay and then count the variable. Delay can be a few milli seconds.Around 100ms.Try increasing the delay slowly and check the results.

  4. #4

    Default

    thanks for your comments.. but it's already too late. I missed the deadline for the project so have actually given up on it for now.

  5. #5

    Default

    HI,
    U might have missed the deadline for the project but try figuring out why did that happen. If u are a student connect a CRO(from college lab) to the out put ofthe IR receiver and check the signal levels for spurious noise. One could also use a schmith trigger for clearing out the signal with a band pass filter. Remember in this world its more important to have a successful failure(one that teaches u) than to have only success which only makes you over confident.

    Asimov

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