problem in display the led using PWM

[abhishekdixit]

hiii,
i am making a project in which i have to glow a led using PWM. i have made a code for PWM for control the brightness of the LED, and its working fine. but when i see the light through digital camera, then it shows flickering in LED brightness. but when i directly glow this LED through power supply, i don't find flickering in LED while showing LED through camera, now i am unable to understand why is it happening?
Please help me.
Thank you



with regards,
Abhishek Dixit

 

[xpress_embedo]

Actually Camera is slower than our eyes.

In Pulse Width Modulation you are controlling the Brightness of LED by varying the pulse width of the signal.
So your eyes are so fast they see all frames very fastly.
But camera is slower than our eyes, and that's why these variations are easily noticeable by camera lens.

But when you glow led directly through supply, camera will not show variation as there are no variations as you are giving constant supply.

 

[abhishekdixit]

arun,
i know that, but now problem is that how should i remove that flickering, i dont want that flickering using digital camera..

- - - Updated - - -

arun,
i know that, but now problem is that how should i remove that flickering, i dont want that flickering using digital camera..

 

[xpress_embedo]

By increasing the frequency of pwm you can stop this flickering.
I am not sure regarding this whether it will work or not.
All the best

 

[abhishekdixit]

hello xpress_embedo
,
i have already done this. but no change in flickering..

 

[FvM]

i have already done this. but no change in flickering..

I don't believe that you varied the PWM frequency sufficiently. Digital cameras are using a "shutter" method to control light intensity. Shutter times can be below milliseconds. To almost remove the flickering, you need to go to high kHz PWM frequencies, e.g. > 10 kHz. Or use a filter capacitor in parallel to the LED, if it's a non-multiplex circuit.