IR Basics Help

Discussion in 'The Projects Forum' started by Chris15, Mar 12, 2010.

  1. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Hello
    I have built a TV Jammer circuit, it has 3 IR LED's, the circuit operates at 4.5V (3x AA's) the problem is that for the circuit to work on the TV it has to be around 30cm, i obviously need more range, how do i get more range.

    Another Question, why can the IR LED in my TV remote bounce off of many walls and still work well i dont have to point it at the TV, can i get my circuit to do this. The LED's in my circuit have a dark blue cover on them, the LED in my remote is clear, if this helps.

    Here is the LED im using
    http://jaycar.com.au/productResults.asp?keywords=ZD-1945&keyform=KEYWORD

    Chris
     
  2. Boo

    Member

    Oct 27, 2009
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    Each LED should have its own resistor, to increase range, decrease the value of R5, what is it presently?
     
  3. Boo

    Member

    Oct 27, 2009
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    Also, why are you using those expensive ones, you can get 100 for 5$
     
  4. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    it is 22ohms, should i use a variable cause i thought i should use 1 anyway could you re do the schematic in paint if possible?
     
  5. Boo

    Member

    Oct 27, 2009
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    Are you sure you chose all the other components correctly? One transistor is NPN and the other is PNP.
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    another way to get more range is to modulate with a carrier of the frequency you like to jam
     
  7. Boo

    Member

    Oct 27, 2009
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    Isnt that what the RC part is doing?
     
  8. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Ok so how would I get the circuit in the same frequency with the tv and is there any way to achieve the wall bouncing effect so I don't have to literally aim it
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    TV IR receivers are tuned to a very narrow frequency range. If your IR emitter is not transmitting very close to the receivers' frequency, it will be ignored.

    They also have circuitry that ignores constant signals of their tuned frequency. You might jam the receiver so that ignores other remote controls, but the signal output from your "jammer" will have to be many times more powerful than the real remote to have the desired effect. It would be more effective if it transmitted at the receiver frequency for say, 16 pulses, and then did not transmit for another 16 pulses. This would confuse the IR receiver's automatic gain control setting.

    IR receivers are tuned to various frequency, but usually in the range of 35kHz to 42kHz. 38kHz is quite common.
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    In other words, you are using "general purpose" IR LEDs instead of the high current ones used in TV remotes and your circuit is far too simple.
     
  11. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Ok so basically i neee a new circuit and better led's, the same sort as found in normal tv remotes? I have another circuit with a 555 and a 10k pot would this be more efficient and have the wall bouncing effect, Chris sorry i cant attatch the circuit as i am on my mobile phone but i can later
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    Oh.
    You are in Australia where many parts are not available, are poor quality and are overpriced.
    You won't find high current LEDs at Jaycar nor at Dick Smith's used car parts and old surplus electronic parts stores.
    Maybe there is a Farnell office in Australia.
     
  13. bertus

    Administrator

    Apr 5, 2008
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  14. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Ok so i need the high current LED's so instead of using a supplier cant i just get them out of old TV remote controlls, and replace them with mine

    And to get another thing clear, is the reason im not getting the wall bouncing because i dont have the high current LED's are they the reason it wall bounces or the frequency

    Chris
     
  15. Chris15

    Thread Starter Active Member

    Apr 15, 2009
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    Oh and here is the new circuit i am going to build
     
  16. Audioguru

    New Member

    Dec 20, 2007
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    Instructables are designed by people who know nothing about electronics.

    That simple circuit uses only 3mA in its IR LEDs.
    A TV remote uses 1000mA and has a supply bypass capacitor so the power supply voltage does not sag when the LEDs are lighted.
     
  17. BMorse

    Senior Member

    Sep 26, 2009
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    And I suppose in Canada the parts are plenty full, higher quality and cheaper than anywhere else, eh?? :rolleyes:


    My .02
     
  18. Audioguru

    New Member

    Dec 20, 2007
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    If I order from Digikey or Newark (they are in the US, a different country than mine) before 8:00PM then it is delivered the next morning. They have EVERYTHING and at good prices.

    RadioShack is gone from Canada. They sold the same garbage at extremely high prices like Jay-Car in Australia and like Maplins in the UK. Their junk does not have any spec's (but they say the weight of every part).

    In Canada we have Sayal which is a surplus electronics store chain from India and we have Princess Auto who sell all kinds of surplus junk like Dick Smith in Australia.
     
  19. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    I've seen the Shack sell plastic flatpack carriers as chip sockets. If we ever introduce something like a VAT (value added tax), parts that go to Radio Shack will get a refund for value lost.
     
  20. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Dick smith sells junk :eek:
    But I thought Australia is one of the finest components sellers.

    I'm lost right now...:confused:
     
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