Turns on LED upon receiving IR signal

Discussion in 'The Projects Forum' started by DutCampos, Jul 2, 2014.

  1. DutCampos

    Thread Starter New Member

    Jul 2, 2014
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    Hi everyone, I'm working on what I think is a fairly simple project. However, I have no previous experience with electronics, so help would be greatly appreciated.

    I have to build two pairs of circuits: an IR transmitter and an IR receiver for each (let's call them pair A and pair B). The IR receiver needs to receive a signal from the transmitter and, upon receiving it, turn on a visible light LED (color doesn't really matter).

    The two catches are: 1) The pairs need to be "unique", meaning that Receiver A can't light up upon receivipng a signal from transmitter B (I think this means I need to modulate the transmitter's carrier frequency). And 2) I need them to be as small as I can possibly make it, especially the receiver.

    Here are some ideas, from what I've read:

    Feel free to disregard all of this if it's stupid or if you have a better idea!!

    a) The receiver would use something like this (https://www.sparkfun.com/datasheets/Sensors/Infrared/tsop382.pdf) of two different carrier frequencies. I would use that to light up a regular LED with a small button-cell battery.
    b) I could use this (https://www.sparkfun.com/datasheets/Components/SMD/DS1077.pdf) to modulate the carrier frequency on the transmitter, maybe?
    c) Build the receiver circuit on this protoboard (https://www.sparkfun.com/products/8886)

    Ask me if you have any questions and thank you for your help!
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    You need an encoder/ decoder chip to transmit data and receive data, using different codes set by links like the HT12D/E series, the VT pin 17 goes high on a valid signal.



    Setup circuits
     
    Last edited: Jul 2, 2014
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  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Are pairs free to roam about or they at a fixed distance & if so, at what distance? Is Pair A Tx, transmitter, physically attached to Pair B Rx, receiver.?
     
  4. DutCampos

    Thread Starter New Member

    Jul 2, 2014
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    Thank you for the help! What would I use the chip with? I mean, what component would actually receive the signal for the chip to decode?

    If you could also tell me what the complete circuit would look like, that would be amazing. But I know that is a ton of work, so if it's too much to ask, don't worry about it.
     
  5. DutCampos

    Thread Starter New Member

    Jul 2, 2014
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    The pairs are free to roam, but don't have to receive each other's signals at all times. If the receiver could light up when ~3 feet or less away from the transmitter, that'd be great.

    They are not connected physically.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    use the infra red leds and receivers as you posted to send and receive.
     
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  7. MrChips

    Moderator

    Oct 2, 2009
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    IR transmitters and receivers operate at standard frequencies, for example, 38kHz.
    You don't alter the carrier frequency to make a unique transmitter/receiver pair.
    Instead, you encode and modulate the IR transmitted beam with a unique digital code using a microcontroller. The receiver does the opposite. It receives the digital code and checks for the unique code.
     
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  8. DutCampos

    Thread Starter New Member

    Jul 2, 2014
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    Alright, got it! Thank you very much, all of you!

    Should I mark this thread as "solved" somehow? Or is that not done here?
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Project information at about 25%.
    Check www.ROBOKITS.CO.IN , under " componets" they have downloads for HT12-A-E-D. The HT12A looks interesting as it can, with a 455kH resonator, output a 38 kHz signal ready to drive a LED driver. Price around US $ 2.60 ea or in rupies 70. It would be helpfull to see someones actual application.
    Is there any political limitation on angle of transmission or reception?
     
  10. MrChips

    Moderator

    Oct 2, 2009
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  11. wayneh

    Expert

    Sep 9, 2010
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    We all appreciate feedback when a project works out, but that's generally the end of it. Of course some posters just disappear and we never know what happened. Not cool, because others coming along later cannot learn from the experiences of those that go before. You can "thank" individual posts when more words are unnecessary, kind of like a "+1".
     
  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Found the IC's at Newark element 14 for $1.37
     
  13. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Sounds like the most basic application for a couple of tiny cheap 8pin PIC chips and a few lines of code.
     
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