Help with Super White LED Dimming Circuit

Discussion in 'The Projects Forum' started by worlda, Nov 9, 2009.

  1. worlda

    Thread Starter New Member

    Nov 6, 2009
    7
    0
    Hi I am looking for some help with a Dimming circuit for a LED board I make for a Video Lamp Here's is the info on the LED used
    Super White LED Specifications:
    Size (mm) : 5mm
    Lens Color : Water Clear
    Reverse Current (uA) : <=30
    Life Rating : 100,000 Hours
    Viewing Angle : 180 Degrees
    Absolute Maximum Ratings (Ta=25°C)
    Max Power Dissipation : 80mw
    Max Continuous Forward Current : 24mA
    Max Peak Forward Current : 75mA
    Reverse Voltage : 5~6V
    Forward Voltage : 3.0-3.2V

    I used 96 LED's 4 LED in series will have a 120ohm resistor Each row so 24 rows 24ma per Row
    I am using 15V 2 Amp Power supply
    Can anyone help with a Dimming circuit for this unit thanks much for any help Charlie
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    You just need a variable 1A power supply that is adjustable from ~12V to ~16V. Almost any DC regulated power supply, linear or switcher, would work.
     
  3. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    you would be better of using a 555 timer circuit to PWM your LED's through a Mosfet, then you can vary the 555's output to dim/brighten your LED's..... this will also lengthen the "life" of your LED's, instead of keeping them constantly "on"....

    My .02
     
  4. sstbrg

    Active Member

    Nov 29, 2008
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    0
    I'm with BMorse.
    PWN is also popular with motor controlling.

    Here's an example of how to configure the LM555:
    http://www.ledmakers.net/show/?id=152
    Pretty much self-explanatory form here, just add the MOSFET part.
     
  5. iONic

    AAC Fanatic!

    Nov 16, 2007
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  6. worlda

    Thread Starter New Member

    Nov 6, 2009
    7
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    thanks all

    does the 555 PWN works with a 15V PS??? or she I use a resistor to lower the voltage to the PWN
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Absolute maximum Vcc is 18v.
    Most datasheets for 555 timers give specifications at 5v, 10v, and 15v.
     
  8. worlda

    Thread Starter New Member

    Nov 6, 2009
    7
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    Any I dead which Mosfet would be best needs output 2.2amps 96LED at 3v 24ms
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Any standard N-channel power MOSFET rated for Vdss=30v or more, and at least 5A Id (drain current).
     
  10. worlda

    Thread Starter New Member

    Nov 6, 2009
    7
    0
    Thanks all for the info one more thing if I want to your Battery,Cads to drive this circuit 12vdc 2.2amps any Ideals on circuit and battery?
    Thanks
     
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