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Simple Infrared LED Switch Help

Discussion in 'LEDs and Optoelectronics' started by amansammy, Nov 21, 2012.

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  1. amansammy

    amansammy

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    Nov 21, 2012
    Hello everyone! This is my first post on this forum.

    Basically I want to make a simple LED lamp which would take about 9V. For it I want to create an Infrared switch so that I can switch the lamp on with any remote(my TV remote mainly!). I have got an Infrared receiver ( TSOP1738 )http://www.erodov.com/forums/imagehosting/221493a3cd13fa7b.jpg
    I also have a 4017 counter, bc547 and bc557 NPN transistors and also common resistors and capacitors.
    Currently I am eyeing this circuit http://embedded-lab.com/blog/wp-content/uploads/2011/07/IR_RemoteCkt.jpg but this is used to switch on AC Appliances.
    Can you give a modification for the circuit to switch on/off the led lamp? Or any other circuit for this? Please help.
    Thank You
     
  2. BobK

    BobK

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    Jan 5, 2010
    You could use the circuit as is, using the relay to switch your LED lamp. But if the LED is not using a lot of current (1A or less) you could just replace the BC547 with a higher power transistor and adjust the base resistor as needed, then place the LED lamp where the relay coil is connected, letting the transistor do the swtiching.

    Bob
     
  3. amansammy

    amansammy

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    Nov 21, 2012
    Would a 2N2222 or 2N3904 will be okay to replace the BC547? And what should be the resistor value? Does it has to be of smaller value or larger? Sorry but I am a newbie in electronics.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The BC547 has a much higher gain than these transistors, but in this circuit I don't think it would matter.
     
  5. amansammy

    amansammy

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    Nov 21, 2012
    would the bc547 be okay? and what about the base resistor? thanks for the quick replys.
     
  6. amansammy

    amansammy

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    Nov 21, 2012
    I don't have a 5v relay. Can I use a 12v relay instead?
     
  7. BobK

    BobK

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    Jan 5, 2010
    What is the voltage / current of the lamp you are trying to switch? This is important for deciding how to do it.

    You could use a 12V relay, but you would have to have a 12V supply then in addition to the 5V supply.

    Bob
     
  8. amansammy

    amansammy

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    Nov 21, 2012
    My lamp actually are 10 3v White LEDs connected in parallel. Each LED takes in 20mA so total current is 200mA. I do have a 12v supply at the moment.
     
  9. BobK

    BobK

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    Jan 5, 2010
    Then just replace the transistor with the 2N2222 and make the base resistor 1K. This would provide a base current of about 3.5 ma which should be enough to saturate the transistor. Connect LEDs + resistors to the collector and the then to the positive supply. No relay needed.

    Bob
     
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