PWM LED Study

Discussion in 'General Electronics Chat' started by Andrew216, Oct 7, 2015.

  1. Andrew216

    Thread Starter New Member

    Jun 24, 2015
    29
    2
    Hello Everybody!
    I'm trying to gain a better understanding on power consumption vs. LED intensity with a range of duty ratios, higher pulsed voltages, and steady-state current. Does anyone have an easy breadboard solution where I can visually see the difference between these as well as on my DMM and O-scope? I'm completely lost on where to even start or what data to even record. Any help is greatly appreciated. Thank You!
     
  2. pwdixon

    Member

    Oct 11, 2012
    488
    56
    If you want to measure intensity you will need a photometer too.
     
  3. Andrew216

    Thread Starter New Member

    Jun 24, 2015
    29
    2
    I have access to a CCD Camera for intensity and uniformity.
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,282
    1,236
    A simple 555 circuit might do it. You can adjust the duty cycle, if you use an adjustable power supply, the voltage and by changing R2 adjust the current.
    http://www.circuitsgallery.com/2013/02/PWM-Led-Dimmer.html
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Its your idea... What do you want to record?
    Frankly not sure why you even need to do so..
    The data is in the datasheet for an LED or is by design of the driver circuit..

    -Luminous intensity across is current rating span is show in the datasheet..
    -A 50% duty cycle will draw roughly 50% less current
    -higher pulsed voltage? not sure what you mean about that.. LEDs are driven by current not voltage
    -steady state current.. read the datasheet
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
    619
    A single circuit won't do everything you want and you're going to need something to measure luminous intensity changes because the human eye can't perceive less than a 2X change in brightness.
    Start with your PWM experiments. At least in that case, everything will be constant except for duty cycle, so you don't need to be concerned with the effect of forward current on relative luminous intensity.
     
Loading...