RGB Controllers

Discussion in 'General Electronics Chat' started by RodneyB, Dec 25, 2014.

  1. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    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.
     
  2. bertus

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  3. ErnieM

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    By "RGB controller" what do you mean?

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

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    Apr 28, 2012
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    I am talking about an LED RGB controller
     
  5. blocco a spirale

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    Jun 18, 2008
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    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.
     
  6. RodneyB

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    Apr 28, 2012
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    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
     
  7. blocco a spirale

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    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).
     
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  8. RodneyB

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    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.
     
  9. blocco a spirale

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    Not by altering the frequency but but by altering the duty-cycle, yes you will be able to produce different colours.
     
  10. RodneyB

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    Is duty cycle the number of times the output on pin3 goes high and low.
     
  11. blocco a spirale

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    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.
     
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  12. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    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.
     
  13. crutschow

    Expert

    Mar 14, 2008
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    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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  14. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    so there is no resistor from pin 3 of the 555 to the base of the BC547
     
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