Connecting leds in Serie unsuccessfully

Discussion in 'General Electronics Chat' started by nic14, Jan 8, 2014.

  1. nic14

    Thread Starter New Member

    Jan 8, 2014
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    0
    Hello All,

    first post here and very new to this world too.
    I am working on a little project at home that require using leds.
    I have bought 3 types of leds, Green, Red and Amber
    according to the specs from the shop I bought them from they are
    5mm with an angle of 25 degree.

    I started, following youtube tutorials, to wire them, by just using wires
    or by using a breadboard.

    I am not sure why but the light the produce is very faint,
    I have the same leds already wired by the shop that work just fine,
    which makes me think I do something wrong.

    Here are some details,

    I used a 9V battery, I connected the positive of the battery to the
    long leg of the led, than the short leg goes to the resistor (360 ohm in this case), the other side of the resistor goes to the negative of the battery.

    This procedure was done with first with all 3 color leds, same result
    than thinking maybe the bread board was the problem I did it without, using wires, and same result

    Than I used a 9V charger connected to the house power, same problem

    Thinking I used the wrong resistor, I checked 4 online calculators, they all tell me the same, to use between 330 and 360 resistors, I tested them both.

    What else can I troubleshoot?

    Many Thanks
    Nic
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Show us how u connected the leds in a drawing.

    I presume u have all the leds connected in parallel.

    Try to connect one LED at a time. The blue ones need a little higher voltage. Means the resistor needs to be a liitle lower. Try 180Ω to 220Ω
     
  3. nic14

    Thread Starter New Member

    Jan 8, 2014
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    0
    Hi, thanks for your reply,
    I only use one led in the circuit, is green and I tested 5 of them.
    This is how I connect it, I just made a quick drawing with my mobile
    since I am at work now, I hope it's clear.

    Thanks
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    What's the value of the resistor in the circuit wired by the shop guys?

    330 Ohms gives you a little over 20mA for 1 LED , which should be ok. Maybe they've given you LEDs which require higher current? Are the components EXACTLY the same they used for their circuit?
     
  5. nic14

    Thread Starter New Member

    Jan 8, 2014
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    The leds are the same, they come from the same package,
    however the wiring is a little different since they get connected to a card that does not require to add resistors, the card has everything incorporated.

    Think what I will do tonight is do some testing,
    start with 330 Ohms and go gradually down to see if there is any difference in brightness.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    umm.. why don't you provide details on this "card"... or is this just something you saw on youtube and hopefully you arent comparing "high power" LEDs (1-5W or more cree/bridgelux,etc.. type) with constant current drivers to a typical cheap 20mA 5mm LED...
    and details on the LED's.. like forward voltage rating and current rating..

    We just assume what you call a 5mm LED is just a typical 2.1Vf 20mA LED..
    Its not going to be "blinding" or very bright at all.. Its just an "indicator" LED and not meant for task lighting or anything like that.
     
  7. nic14

    Thread Starter New Member

    Jan 8, 2014
    9
    0

    Hi,

    the first link is the card I use, I connected with the leds and works perfectly, but than I did not have to do much, just know in which hole to put the wire.
    http://www.aviationmegastore.com/b7...f4667&action=prodinfo&parent_id=278&art=61099

    the second link is for the leds, absolutely the same ones I used for the card, as mentioned they come from the same bag
    http://www.aviationmegastore.com/le...4667&action=prodinfo&parent_id=278&art=102900


    I admit, I found it strange, but I cannot explain it.
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    The card might be having appropriate resistor for each LED

    By the way, blue LEDs require lower resistance than other colors
     
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    looks like a regular 20mA LED to me..
    according to the card "low" = 5mA supply to the LED and "high" setting = 10mA to the LED..

    So you clearly did something wrong as 20mA to the LED would be brighter than what you see with the "card"..

    any chance you are reading the resistor color codes wrong.. Maybe you have a 3.3K ohm or something
     
  10. nic14

    Thread Starter New Member

    Jan 8, 2014
    9
    0

    OK, so I got home and tested,
    let me start by saying that I am new at this and all the terminology around electronic,

    turns out mcgyvr, that you are totally right, I bought the wrong resistor box selection, so instead of using the 330 ohms I was using 330k ohms,

    who knew that few extra thousand ohms would make a difference.... :)
    I had some old 60 ohms resistors that my friend left with me once, I tested it with 3 green leds in series and worked just great

    Today I have learned something really cool, at least for me,
    and it's all thanks to you guys...

    I really appreciate your help and teaching

    Nic
     
  11. trader007

    Active Member

    Feb 27, 2010
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    its only off by a thousand times, it should have worked perfectly
     
  12. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I win... mmuuhhhaaaaa. happy dance..

    FYI.. going over the current for an LED will drastically shorten its lifespan.. If a particular LED is not bright enough.. Find a brighter one or one that can tolerate higher current. Don't over drive them..
    That LED should be no more than 20mA.. And most of us feel that 10mA is plenty.. So go back to the 330ohm resistor.
     
  13. nic14

    Thread Starter New Member

    Jan 8, 2014
    9
    0

    understood, I have now ordered the right ones, thanks for the tip.
     
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