Infrared Diode

Discussion in 'General Electronics Chat' started by sirch2, Feb 25, 2013.

  1. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    I'm looking to use an infrared LED and photodiode as a simple switch, i.e. turn the LED on and across the room the some other device turns on.

    I've read around the subject and there are some devices that need a 38kHz signal to for the receiver to respond but I cam across this deivce - http://www.soselectronic.com/a_info/resource/d/sfh203.pdf - that would seem to be a simple photo diode.

    Questions are:

    • can that device work with out a 38kHz signal?
    • what would be a good circuit for switching based on that device?
    • are there any disadvantages (I assume the 38kHz is there to filer out environmental "noise" from other IR sources)?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    3,362
    It depends on how much reliability you desire.

    A simple IR LED and IR sensor will work but not very reliable.
    The next step is to drive the IR LED at 38kHz and use the appropriate IR detector.

    TV/VCR remote controllers use this scheme as well as they send digital data which can be checked for data corruption.
     
  3. sirch2

    Thread Starter Well-Known Member

    Jan 21, 2013
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    351
    Well, I figured it would work with the right circuit. As for reliability, it's not that critical in as much as the remote device either comes on or I need to send the IR pulse again. As long as it works most of the time it's not really an issue.

    Any thoughts on a circuit? One solution I'm thinking about is using the IR photodiode to control the base of a suitably biased transistor.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,023
    3,236
    You can use most common photodiodes or phototransistors for your circuit.

    You will likely need a visible light filter (dark red) to avoid triggering from ambient light.
     
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