RGB Controllers

Thread Starter

RodneyB

Joined Apr 28, 2012
697
I want to build an RGB controller. I don't want to buy it off ebay or any similar site. I want to understand the theory behind it and then build up a controller. Its important to me understand this.

Can someone point me in the right direction to start learning about RGB's and there controllers.
 

ErnieM

Joined Apr 24, 2011
8,377
By "RGB controller" what do you mean?

Is this a single LED, a billboard video monitor, or something else entirely?
 

blocco a spirale

Joined Jun 18, 2008
1,546
What is the control input to your proposed controller; i.e. manual control or via some sort of interface from another device?

Do you prefer a PWM or a linear controller?

Solving the problem for one LED solves for all three so this is barely any more complex than any single LED brightness controller.
 

Thread Starter

RodneyB

Joined Apr 28, 2012
697
I am trying to learn about PWM and thought an LED controller would be best to learn with. I don't understand anything about it and was looking for a PWM for absolute beginners. Anything to learn from possibly with simple circuits to demonstrate as you learn to build
 

blocco a spirale

Joined Jun 18, 2008
1,546
I think the link that Bertus provided in #2 is a good place to start and is a good method for generating multiple PWM signals, it can also be done using a 555 timer (google 555 pwm).
 

Thread Starter

RodneyB

Joined Apr 28, 2012
697
If I were to get 3 x 555 running as PWM and connected each of the LED Legs, Red, Green and Blue to different outputs. By Altering the frequency on the separates IC's would I get different colours.
 

blocco a spirale

Joined Jun 18, 2008
1,546
If I were to get 3 x 555 running as PWM and connected each of the LED Legs, Red, Green and Blue to different outputs. By Altering the frequency on the separates IC's would I get different colours.
Not by altering the frequency but but by altering the duty-cycle, yes you will be able to produce different colours.
 

blocco a spirale

Joined Jun 18, 2008
1,546
No. The duty-cycle is what PWM is all about. It is the Width of the Pulse. Pulse Width Modulation, right?

By varying/modulating the width of the pulse (within a fixed period) we control the amount of energy imparted to the load.
 

Thread Starter

RodneyB

Joined Apr 28, 2012
697
I have found a circuit using a 555 IC to make a PWM. I also have a roll of RGB LED strip lights rated at 12 Volts the strip already has resistors on the Strip

If I was t build 3 of these attached circuits and connect the to red green and Blue respectively switched through the transistors circuit attached would this be a start to learning and understand PWM.
 

Attachments

crutschow

Joined Mar 14, 2008
34,282
Those circuits should work to demo PWM.
Note that you are using the transistors as emitter-followers so you don't need resistors R11, R12, and R13.
 
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