Hello fellow users,
I have a project i want to build which will include controlling LED's brightness by "voltage dimming" method where the circuit reduces the voltage of the led instead of using a PMW approach, such that i get no flickering. What wizardry do i need to do to be able to control lets say the voltage of 100 LED's using the arduino. What hardware can I use, that doesn't involve the LED's receiving a PMW signal, rather just a decreased voltage signal.
First of all, controlling the voltage of a LED is not a good idea. LEDs work on current, and every LED can have a different voltage with the same current, with different temperature etc. That's why a current limiting resistor is required for every LED. With that resistor a high voltage may be required to make the LED shine, higher than the Arduino can provide.
Most Arduinos don't have a true analog output, that's why PWM is used instead.
Powering one or a number of LED with an adjustable voltage requires an adjustable power supply. Using a transistor for the power source will burn excess voltage in that transistor.
In either case you should understand more about electronic circuits, or use light strips with built in controllers.
Why did't you reply to your previous thread.
PWM control generally speaking does not flicker, at least not for humans.
The other option is current control (not voltage control).
Need to know what type of LEDs you're talking about.
Leo..
Thanks i didn't even remember that i have posted about a similar matter before. Thanks Wawa and DrDiettrich.
Any flickering you are seeing is likely due to the software changing the brightness in too large of a step. PWM happens at frequencies faster than the human optic system can react (~500Hz) so you won't see a flicker (well, if you are an insect, you might.) But our optic nerve and decoding wet-ware is just too slow for that. 30-60Hz from fluorescents is just barely below the limen.
If you are seeing the pulses with some sort of instrumentation (or you ARE an insect!) then you can filter the PWM with a resistor (~4K7) then a capacitor (~103) to ground, to provide a steady DC voltage.
Yer welcome Tillmarkowitz.
PWM is favorable because it's supported by the hardware, and thus incredibly easy.
I have always found common cathode multi-LEDs to be more straight forward to use, but they are both workable.
ps, cathode means the negative electrode. Cathode rays were named in the late 1800s before the nature of electrical current was fully understood. Here's Crooke's cathode ray tube, the negative electrode is attached on the right side - electrons go through the slit. If I hook it up backward, the line does not appear:
Cool, I will try draw up some circuitry and maybe a code for a common cathode Led controlling system. I will do the same for current control too and then maybe do some experimenting to see which path i will choose.
Thanks!