791Views7Replies

Author Options:

Controlling 10 RGB LEDs with three pots(with out a microcontroller)? Answered


hello i was just wondering if it was possible to wire 10 rgb leds together run all the red leads to one pot, the blue to another, and the green to the third, and have all of the leds colors controlled by turning the pots.
Any information would be helpful. I am intending to use this as lighting on my head board in my room.  Id be using 5mm UltraBright RGB Tri-color LEDs
Thanks to all who reply.

Discussions

0
None
steveastrouk

Best Answer 8 years ago

Try three circuits like this. Its inefficient, at low brightnesses, because the 317 dissipates all the power the LEDs aren't using.

trimmable current source.JPG
0
None
the seakersteveastrouk

Answer 8 years ago

If im not mistaken, the link that frollard posted uses this same idea?

0
None
steveastroukthe seaker

Answer 8 years ago

Well this is my work...its simpler than Frollard's link.

0
None
frollard

8 years ago

It IS possible, but its not very elegant and will require similar/more parts than just using a uC. The reason being that the leds need current. To maintain their voltage they need x amount of current to flow from the supply. To dim them, the pot has to dump a portion of that current as heat (they're not very good at dumping a lot of current). When the leds are nearly off, the pot is nearly burning up.
To get around this you use a pot to drive a curent limiting led driver.  this instructable does exactly that.  It's as simple as you will find.

0
None
the seakerfrollard

Answer 8 years ago

Thank you very much for the reply, This is almost exactly what i was looking for.

0
None
rickharris

8 years ago

It would be almost impossible to control the brightness of the LEDs directly by adjusting the current with a POT - There simple isn't enough resolution in the POT.

if you are determined to avoid microcontrollers then a 555 pulse width controller may be a solution - ccts on line.

for an easy microcontroller solution look at http://www.picaxe.com