Newbie Question: LED in parallel

Discussion in 'General Electronics Chat' started by Delita, Dec 28, 2009.

  1. Delita

    Thread Starter New Member

    Dec 28, 2009
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    Hi all!
    I recently became interested in building electronics, and I have a question about having an LED and a switch in parallel.

    I built the following circuit in a program called Yenka:
    [​IMG]
    My question is, since the LED is parallel with the switch, why doesn't current flow through the LED regardless of the state of the switch?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Delita

    Thread Starter New Member

    Dec 28, 2009
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    thanks for the response, and useful reference material =)
    however, the LED gets 0amps when the switch is pressed, and I'm still unsure why that is
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    When the switch is closed, all the current will go through the switch as its resistance is much lower as the leds resistance.
    When the switch is opened the current will flow through the led, if the led voltage is lower than the 3 Volts.
    The currrent will be (3 - Vled) / 100, in your case.
    If the led voltage is higher than 3 volts, hardly any current will flow through the led.

    Greetings,
    Bertus
     
  5. Delita

    Thread Starter New Member

    Dec 28, 2009
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    ahhh, of course!
    Thank you, I must not have been thinking straight =/
     
  6. bertus

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  7. Wendy

    Moderator

    Mar 24, 2008
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    I've used voltage dividers to turn an LED off before, it used more wattage, but it was very similar to your concept. I explained it in this article I wrote a while back (and is still a WIP).

    LEDs, 555s, Flashers, and Light Chasers
     
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