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PN-junction diode vs light emitting diodes

  1. Nov 17, 2014 #1
    Is it advisable to use an LED instead of a PN-junction diode and what is the resistance of each (or do they vary)? The only reason I'm asking is LEDs are easier and cheaper to get.
    P.S. What I need it for, only needs a PN-junction diode.
     
  2. jcsd
  3. Nov 17, 2014 #2

    mfb

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    Different parts will have different resistances, different threshold voltages, different current and heat they can tolerate, different sizes, different reverse breakdown voltages, ...
    This is impossible to answer in a general way.
     
  4. Nov 17, 2014 #3
    Hmm, ok but is it advisable or not?
     
  5. Nov 17, 2014 #4

    donpacino

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    So an LED is a PN junction diode, its just light emitting......

    So you are saying you need to use a diode in circuitry, but you replace the regular diode with an LED....
    as long as they are electrically equivalent and meet thermal and package requirements there is nothing wrong with that.
     
  6. Nov 17, 2014 #5

    dlgoff

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    It just amazes me that after such a good answer that you still get ...
    Just sayin'
     
  7. Nov 17, 2014 #6
    The answer was a little vague and did not completely answer my question
     
  8. Nov 17, 2014 #7

    Averagesupernova

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    The question was a little vague and was not possible to answer completely.
    -
    Think of it this way: All LEDs are diodes, not all diodes are LEDs. To say that you could replace an LED with a diode seems silly of course since the idea of an LED is to be able to emit some type of visible or infrared radiation. There can be instances where a diode can be replaced by a simple LED such as a rectifier with low current draw load. However, there are many many many types of diodes besides LEDs. Small signal and switching diodes, power rectifiers that can handle hundreds of amperes, diodes that can switch up to a rate in the microwave region, PIN diodes used to switch RF currents, varactor diodes that are used as variable capacitors, etc. etc. Most if not all of those examples could not be substituted with an LED. There is no one size fits all here.
     
  9. Nov 17, 2014 #8

    dlgoff

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    I apologies for coming off so strong in my comment. It's just that I would have liked to have seen your next question showed that you had researched the differences mfb allotted to; in relation to your diode needs.
     
  10. Nov 17, 2014 #9

    NascentOxygen

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    Not usuallyadvisable.
     
  11. Nov 19, 2014 #10

    meBigGuy

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    No.
    No way.
    No how.
    LED makes a poor general purpose diode.
    Compare the specs for reverse leakge, reverse breakdown, forward drop, dynamic resistance, switching times, etc etc etc.
     
  12. Nov 19, 2014 #11
    But isn't the ordinary diode also emit a light in form of Heat (IR light) ;)
     
  13. Nov 19, 2014 #12

    mfb

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    That is a completely different mechanism.
     
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