IR Communication by using PT2248/PT2249A

Discussion in 'Bob & Don's Electronics Forum' started by munhann, Jul 6, 2011.

  1. munhann

    munhann New Member

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    Location:
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    HI All,
    Recently i build a IR communication circuit and still fails to figure out what went wrong..
    I hope can get your expert help on this. Below are component list and attach files is my circuit schematics. Please help and this is urgent!! :(

    TX IR Component List
    - C1 = C2 = C3 = 120pF, C4 = 10nF (Polarized Capacitor)
    - XTAL = 455Khz
    - D1 = IN4002 and D2 = IN4148
    - Q1 = Q2 = PNP A1015
    - LED0 = Infrared Transmitting LED

    RX IR Component List
    - C1 = 100pf
    - R1 = R2 = 39K
    - 1738 IR Receiver (38Khz)
    - PNP A1015
    - Receiver IR Sensor

    Attached Files:

  2. DonL

    DonL Jack of all trades Master of one

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    Welcome to Terry's Forums munhann,

    You can verify the IR transmitter is working, using a cell phones camera, You should be able to detect and see the IR.

    The output going to the 2313 has to be at least 2 wires, Your drawing only shows 1.
    You would need a ground return path for that output feeding the 2313 microcontroller.
    Or is it on a common power supply ?


    Enjoy your project.


    DonL
    Last edited: Jul 6, 2011
  3. jimbo

    jimbo Plumber

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    I think you used putty instead of silcon on the XTAL, and the drain for Q2 needs to be 2" The whole thing is not vented.
  4. BobL43

    BobL43 DIY Senior Member

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    Leaky circuit

    Jimbo, now you sound like a plumber talking ;) And those 2 little arrows pointing out of the Light Emitting diode is the vent.
    Last edited: Jul 6, 2011
  5. BobL43

    BobL43 DIY Senior Member

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    Munhann,

    I see the tuned circuit on the remote sender oscillator is crystal controlled; is the r/c tuned to the same frequency?

    38KHz you specified as the receiver and the transmitter's crystal is 455KHz, the (almost) 12th harmonic of the receiver. I forgot most of this stuff 40 years ago, but maybe what I said will ring a bell for you. Was this a kit you built?

    And what Don said too
    Good Luck

    Bob
  6. DonL

    DonL Jack of all trades Master of one

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    It looks like all the parts used are correct.

    The receiver has a built in Frequency Divider, and the 38khz is fine for the IR Band.
    The 455Khz is used because you can get them easy, Most are ceramic resonators and not really crystals.

    jimbo is correct tho "The whole thing is not vented."
    There is no place for the smoke to be released properly.

    If it passed the smoke test, then I would recommend getting the O-Scope out.
    It is hard seeing them electrons without the proper equipment.


    DonL
  7. BobL43

    BobL43 DIY Senior Member

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    I googled the chips, and this post looks like a cut and paste form the datasheets.

    as long as the thing is not in an enclosure, the factory smoke should be able to be released without a draft inducer fan. Just keep your face away from the board when it gets energized.

    by the way: URGENT?
  8. DonL

    DonL Jack of all trades Master of one

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    Do you have a link to that info Bob ?

    It sure looks like a waste, if that is the only part of the chips being used.

    I think I would have gone with a optic isolator. that would eliminate a lot of outside interference.

    What are you building Munhann ?

    What is your 2313 microcontroller doing with the data that it receives ?

    Hello Come in, Can you hear me now ? ...---... ...---... ...---...


    DonL
  9. BobL43

    BobL43 DIY Senior Member

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    Last edited: Jul 6, 2011
  10. DonL

    DonL Jack of all trades Master of one

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    Thanks Bob,


    Maybe Munhann will come fill us in on his project.

    It looks like a secret project. Over kill from what I can see, using that chip setup for 1 function.

    There must be a method for the madness. I am not knowing...


    DonL
  11. munhann

    munhann New Member

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    2
    Location:
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    Sorry not details given. Below are ideal IR transmitter design stage; But after i build up whole IR transmitter circuit, i found that IR LED no voltage due to Q2 Transistor Emitter no voltage (Base and Collector have nearly same to 2.5v).. i not sure it is design problem or somewhere connection wrongly..

    Operation Mode
    - This circuit only require 3v DC Supply. 3v Lithium used for this design.
    - C4 used for power supply filters purpose.
    - When switch is open, the whole circuit in very low power or sleep mode to achieve low power consumption. Whole circuit only operate mode during switch close mode.
    - IN4002 Diode applied reserve voltage 4v DC to work act ensure current flow in one direction and block the reverse current flow back.
    - IN4148 Diode used for high-speed switching and used to trigger C1 (T1) to be “1†which able to communicate with IR Receiver through matching serial code bits.
    - From the PT2248 datasheet, basic transmitting waveform consists of 12 bits serial data (3 code bits, 3 single short code and 6 keys input code). Carrier frequency is dependent on the oscillation frequency (Fosc) and is given by following formula;
    A= (Fosc/12) Hz
    So in order to get 38Khz, 38*12 = Fosc = ~455Khz (XTAL) must be used.
    - When (TXOUT)’ in high (1), Q1 transistor (PNP) emitter and base reverse biased so emitter and collector act as open circuit. No current flow into Q2 transistor and LED0 is in Off Mode.
    - When (TXOUT)’ in low (0), Q1 transistor (PNP) emitter and base forwards biased so emitter and collector act as close circuit. Current flow into Q2 transistor and LED0 is in ON Mode then signal will be transmit to IR Receiver.
  12. DonL

    DonL Jack of all trades Master of one

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    If Q2 has 2.5 Volts on Collector and Base, then the emitter should have about 1.8 volts, and the LED should be on.
    That is if the transistor is a NPN installed properly and is good.

    I would double check the pin out, because it sounds like it is not inserted or pined properly, wrong type or is bad.


    Have a good day.


    DonL
  13. BobL43

    BobL43 DIY Senior Member

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    Even if the LED is on and sending out a "carrier beam" at the carrier frequency, doesn't it need to be modulated with some data for the receiver to interpret? I am not saying I know how these remote devices work, but with the capabilties these 2 chips have, it looks like the receiver is going to be looking for something it understands to give an output. To be honest, I have not yet looked at the Attiny 2313 device to see what it is and what type input it looks for. A demodulator? I will look.
  14. BobL43

    BobL43 DIY Senior Member

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    OK, I looked: Attiny 2313: www.atmel.com/dyn/resources/prod_documents/doc2543S.pdf
    It is a microprocessor that needs a compiled program loaded into it. Perhaps with an "empty brain" it knows not what to do. Did you load a program into it munhann? did you look at any of the stuff you built with an oscilloscope as Don suggested?
    Interesting stuff, but at my age, 68, it is just that to me: interesting. I wish I knew more to help you.
    I will follow this thread, but at this point I cannot contribute much except google search hits :) I used to work with lots of discrete component linear and digital circuits, and then on to IC circuits, but that was a LONG time ago.
  15. DonL

    DonL Jack of all trades Master of one

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    Yes Bob You are correct.

    The fact that the transistor is not conducting is the first problem.

    That needs to be corrected first. There could be other problems also.

    When a sub part is used, then the EBC pins are sometimes swapped, depending on the Package type and manufacture.


    Have a Great day.


    DonL
  16. DonL

    DonL Jack of all trades Master of one

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    Terry needs to make an Electronics Forum.

    That way we don't mess up the Electrical Forum, With the Good stuff.
    And the argument about Ground Fault Interrupts can continue with out Interruptions.


    Just my thought.


    I hope everyone is having a great day. We missed you JW I hope all is well. Don't let your meat spoil.


    DonL
  17. BobL43

    BobL43 DIY Senior Member

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    Don, you are right about maybe an electronics thread.

    And I agree with you on the Casey thread; everything you said. Just don't bust a gut over it; there should be a bullshit thread and all those USA bashing posts by Ian moved to it.
  18. DonL

    DonL Jack of all trades Master of one

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    LOL , I just blew my top.

    Guess my blood pressure went high.

    Went to health and wellness and it just went higher.

    Guess i need some crack...

    My girl will be home soon. She will take care of the pressure.


    Enjoy your weekend.


    DonL
  19. DonL

    DonL Jack of all trades Master of one

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    [​IMG]

    Your Parts list says Q2 is a PNP, While the schematic shows a NPN.

    That could very well be your problem. You may want to double check that because it has to be a NPN.

    The part number for Q2 should be 2SC1815.


    DonL
    Last edited: Jul 9, 2011
  20. BobL43

    BobL43 DIY Senior Member

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    Good catch Don. Base polarity is an important thing. So what do they call that output, a cascaded emitter follower or something like that?
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