This simple RGBled color mixer uses NO microcontrollers( Arduino - Pic etc ). It controls the brightness of each color channel by varying the duty cycle (On time vs OFF time) by a technique named PWM or pulse width modulation. This results in a very low power dissipation, as leds are either fully on or off. The circuit manages the three channels with only 1 common integrated circuit and 2 transistors.

Step 1: RGB Controller at Work

Step 2: Complete Circuit Diagram

Main components:

IC1: TL084 (quad FET input op-amp)

Q1: BC558 (general purpose PNP transistor)

Q2: BC548(general purpose NPN transistor)

D1-D61N4148 diodes

VR1-VR3 10Kohm Linear potentiometers

LED: RGB common cathode led

Step 3: PUT Oscillator (sawtooth Generator)

Step 4: Comparators 1-3

This in turn determines the time each led will be ON during each sawtooth oscillator cycle, making it appear to be brighter or darker to the eye.

Step 5: Driving RGB LED

For this demo I am driving the LEDs directly from the OP-amp, but you can drive any power leds, by adding a power mosfet or transistor.

Step 6: For More Details & Waveforms Watch the Video

Step 7:

I am slowly learning how to read these. Can you list a total parts list you used in this project?
I have been looking for a circuit that does not involve an Arduino. Is there a way to see how this was constructed?
<p>You will find the circuit diagram in<strong> step 2 </strong>and also a video in <strong>step 6.</strong></p><p>greetings!</p>
I really would like a quick reply, great project! I have been looking all over the internet and when I see these controllers with arduinos and I cant understand what it could need it for, all it does is vary the power going to pins of the led, a switch could do that. Well, i'm happy I found this, but I have never done any circuitry. Looking at the schematics makes my head hurt, could you possibly do a different schematic that is more wire and component pictures? Dont email it, I dont use email. It would help more than me if you could add that schematic to the project along with pictures. I know I sound like a noob but I really would like to do this!
<p>A single view on the schematics and I've remebered the style: You are the guy with the everlasting LED! Glad to see you again here. It's truely amazing what you are doing with basic components.</p><p>Keep rockin' ! :D</p>
<p>Hi !</p><p>Thanks again, there's a lot more coming, please stay in tune !</p>
<p>What... no microcontroller but actual discrete components???? I feel like... i am young again :-)</p>
<p>Yeah! no GOTO, MOVLW OR BTFSS... just plain ol' leads you can bend &amp; solder!</p><p>( I'll be posting some of the others too ) :-)</p>
<p>This is awesome! And those sliders look so cool! I honestly never thought to use PWM for mixing colors on an RGB LED. </p>
<p>Great !!</p>

About This Instructable




Bio: Music: my profession for over 40 years... Electronics: my beloved hobby always.
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