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RGB LED Ring Light

I want to build a RGB LED Ring Light for my Photography sessions. I'm going to order 20 RGB LED's and i want to make it as simple as possible. 3 Potentiometers to control RED / GREEN / BLUE Values. What would be the best way to power 20 RGB LED's? Still wondering if Im going to use a Microcontroller or just directly feed power thru the the potentiometers and to the LED's. Thank yoU!

frollard6 years ago
Since you're using it for photography, you do want a setup that doesn't use pulse width modultion, because the flicker from the digital-on-off will show up differently to a fast shutter than it does to our eyes.

Unfortunately, this means you need a more wasteful setup that has the led powered, and a massive transistor burns off excess power as heat to dim the led. It's better for flicker, worse for efficiency.

https://www.instructables.com/id/Power-LED-s---simplest-light-with-constant-current/
--it's possible to put a potentiometer into that circuit to change the bias voltage on the transistor to brighten or darken the light.
For the simplest solution, which is linear electtronics use the circuit I am attaching. Check out the math, and put the right numbers in for your LEDs. You need to know the forward volt drop of each LED in each colour to do the maths for the circuit.
Copy of maths.jpgtrimmable current source.JPG