PWM LED Study

Thread Starter

Andrew216

Joined Jun 24, 2015
29
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!
 

ronv

Joined Nov 12, 2008
3,770
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!
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
 

mcgyvr

Joined Oct 15, 2009
5,394
I'm completely lost on where to even start or what data to even record.
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
 

dl324

Joined Mar 30, 2015
16,846
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?
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.
I'm completely lost on where to even start or what data to even record.
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.
 
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