power problem: IR receiver and transmitter

Discussion in 'The Projects Forum' started by incubus, Nov 23, 2009.

  1. incubus

    Thread Starter New Member

    Nov 22, 2009
    5
    0
    Hi,
    I already have the ir transmitter circuit and tsop receiver circuit as shown.

    [​IMG]

    [​IMG]

    They both need a supply of 5v dc.

    The problem is when i connect them both to the supply (in parallel):

    1. the receiver can't detect the emitter.
    or
    2. the receiver is not working.

    I know that the ir emitter is working because i checked it through my phone's camera and i can see the purple light.

    so i tried to use 2 power supplies. 1 for the emitter and 1 for the receiver.

    It worked.

    but i want them to have only 1 dc supply of 5v... so what should i do?? :(
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The schematics are of limited utility with no component values attached. If the frequency is not very close to 38 KHz, the receiver will not respond. There is no way to key or modulate the 555's output.
     
  3. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    Most Transmitter Receiver Units have separate power supplies anyway, if you are going to place the transmitter next to the receiver, why make it wireless? Why not make a corded remote?

    When you connected them in "parallel", how exactly did you connect them to power?? Did you connect the V+ for bot units to the Positive side of the power supply and both grounds to the Negative side of the power supply??
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    You need a pullup on the IR output.
     
  5. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    That would not solve the OPs problem with the power issue.....
     
  6. incubus

    Thread Starter New Member

    Nov 22, 2009
    5
    0
    Hi BMorse and beenthere! Thanks for the reply.

    Im working on a mobile robot. therefore it should be wireless.

    I'm 100% sure that they are working when they have a separate supply. Its because i tested it already.

    and yup, the V+ of the transmitter and receiver are connected to the + supply and their ground to the - of the power supply.

    I think the problem is in the transmitter circuit. Because capacitors there are directly connected to V+ and ground. Maybe it affects the receiver circuit.

    i really really want them to have only 1 supply. and its also because some are saying that it is really possible.

    hope you guys help me.

    Thanks in advance!
     
  7. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    Try connecting your receiver this way, and then try using both off of the same power supply..... the 100ohm resistor and the 47uF capacitor with "clean" up the line to reduce power supply noise if there is some coming from the 555 timer circuit....

    If you are going to use this for robotics, the 555 transmitter circuit will not do you any good, unless you are just looking for a Modulated 38Khz signal with no encoded data in it, but then that would only give a go/no go signal.... if this is for robot communication, you need a microcontroller to modulate the transmitter data and send it to the receiver circuit, so this way you will have more flexibility with the data transmission....

    Unless you are using this as an object detector, then it will work quite well for proximity detection of objects...
     
  8. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    R2 should be on the 5V line directly not after the 100ohm resistor.

    And you're right, the AGC on the TSOP will not like a steady 38kHz signal.
     
  9. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    BlueRoom is correct, I was just quickly putting this together so I inadvertently placed the 10K on the wrong side of the 100 ohm resistor.....
     
  10. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    1,758
    98
    Just a sidenote some TSOP chips have a 30K pullup built in, but not all. So check the datasheet. I suspect BMorse has nailed it with the continuous signal as being the culprit.

    You should be able to test the receiver with almost any TV remote control.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    here is an updated schematic with the correction for the placement of the 10k resistor... I thought it would be more appropriate this way, so not to throw off anyone else reading this thread if I would have just changed the first circuit....
     
Loading...