Few questions about homemade IrDA module

Discussion in 'The Projects Forum' started by Gorstak, Feb 17, 2010.

  1. Gorstak

    Thread Starter New Member

    Feb 17, 2010
    2
    0
    First of all, I'm not an electrician, I'm a medical student who occasionally grab a soldering iron for some fun. So if I'm asking something really stupid, I'm sorry.
    I found scheme forIR transciever on http://www.hardwaresecrets.com/article/86/2 and I'm plannig to build it. I was wondering is it ok to rearrange circuit (attached picture, left side) in order to bring photodiode and LED physically close and to reduce wiring, and is there a "wrong and right" way to connect photodiode and LED (I mean does polarity matters and how can I distiguish anode from cathode)
    Thanks everyone :)
     
  2. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    Physical closeness should be fine, do not let a photo diode see something it should not.

    Polarity does matter. Usually marked with a flat side on the diode, a longer lead.... look at the spec sheet. Failing that use a multimeter. Conventional ( as in physics ) current flows from + to - the same direction as the arrow on the diode. The low ohm range should do ( and some have a diode test range ). Slight problem is knowing which lead on the meter is + and which is -. Modern meters are usually + on red, and - on black or common. A second meter can be useful for this. Or use a battery with a current limiting resistor.l
     
  3. Gorstak

    Thread Starter New Member

    Feb 17, 2010
    2
    0
    In case the polarity of a diode is reversed, will it only break the circuit or is there a risk of damaging the components. The circuit uses 5V lead from motherboard.
     
  4. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    Diode will probably be ok, but will not emit light or give expected response to light.
     
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