led equalizer help!

Discussion in 'The Projects Forum' started by anomalyz, Apr 29, 2010.

  1. anomalyz

    Thread Starter New Member

    Mar 21, 2010
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    0
    I currently have 4 leds in series that are connected to a transitor that allows the leds to pulse to music. I am trying to figure out how to have each led light up with the voltage rises. Ex. 1st led lights up at 3V 2nd at 5V 3rd at 7V and 4th at 9V. I am unsure on how to connect the leds together please help.
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,652
    2,348
    Hello,

    Did you already have a look at the LM3914?
    That will let you connect upto 10 leds.

    Bertus
     
  3. anomalyz

    Thread Starter New Member

    Mar 21, 2010
    6
    0
    Im looking for a way to do it with out any special chips!
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,652
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    Hello,

    Do you want to use opamps or comparators?

    Here is a schematic I made some time ago for a thermometer.

    [​IMG]

    The number of opamps can be changed.
    Also the voltage steps can be adjusted.

    Bertus
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You would actually be better using an LM3915 logarithmic dot/bar display driver.

    Our hearing is not linear; we can hear from very quiet sounds to very loud sounds. If you use a linear scale, it will seem as if there is hardly any difference in the sound level between the first LED lighting and the highest LED lighting.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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