IR Sensor Help

Discussion in 'General Electronics Chat' started by Guinness, Dec 17, 2010.

  1. Guinness

    Thread Starter Member

    Dec 31, 2009
    81
    1
    Hi,

    I am trying to make a switch using IR as the trigger, when the beam between the IR LED and the reciever is broken, the switch is activated. But I seem to be stuck right at the start, I have been given a load of IR recievers ( work ordered wrong part number, lucky me ). They are from RS order number: 654-8930. I have looked at the data sheet to try to figure out how to use them, but the bit that is confusing me most is the 38Khz carrier frequency it uses.

    1. Can I use a normal IR LED to transmit ro it?

    2. Does the 38Khz mean I have to make a special ciruit for the reciever to work?

    I have tried to search the net and this web site, but cant seem to find the answers I need.
    If anyone could help that would be great.

    cheers.
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,789
    945
    Description
    SFH 5110 is a IR receiver to detect light from
    infrared remote control systems. The IC includes
    photodiode, preamplifier, automatic gain control,
    bandpass and demodulator.

    It's a complete package, so yes the IR signal would need to be modulated. A 555 timer could fill the bill. Or would it be Bill? :)
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I expect you will find that this receiver will respond to your ordinary TV remote control.

    hgmjr
     
  4. Guinness

    Thread Starter Member

    Dec 31, 2009
    81
    1
    Cheers, I am using a uC in circuit, so will use the PWM on that.

    Thats something I need to watch out for then, cheers.

    So im guessing I can just pulse the IR LED at the reciever at 38Khz to keep it activated untill the beam is broken? Or is there a whole setup of intial pulses for the reciever to recognise it first?

    Sorry but im new to wireless communication.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,789
    945
    The data sheet simply showed a high sq wave type pulse output that lasts for the duration of the modulated input. So any modulation within the freq recognition range of the IR chip will produce a steady high output for the duration of the input. If the range is very tight, your uC might need a crystal to have the stability to stay within the freq range over all operating voltages and temperatures..
     
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