RGB Controller Using 555 Timer

LEDs are the long-lasting, energy-efficient, and cool-to-use light sources that will illuminate our planet for many years to come.

An RGB LED is an LED module that can produce almost any color using these three primary additive colors: Red, Green and Blue. The simplest version of an RGB LED has a combination of 3 separate light-emitting diodes in one package, housed under a clear protective lens. This LED package will have 4 pins, one for each of the three colored diodes and one common anode (+) or cathode (-).

The color of the RGB led can be controlled by using PWM (Pulse Width Modulation). In which duty cycle (measure in %) of signal is changed.

100% duty cycle = maximum brightness of LED

0% duty cycle = zero brightness

PWM can be generated using micro-controller such as Arduino, STM, PIC etc or using 555 timer IC.

In this tutorial we are using 555 timer IC to generate variable PWM to change color of single RGB led using potentiometer.

• 3 x 555 timer IC
• 3 x 1K ohm resistor
• 3 x 330 ohm resistor
• 3 x 5K ohm potentiometer
• 3 x 100nF capacitor
• 9 x 1N4148 diode
• 1 x RGB LED (common cathode)
• 1 x breadboard
• 6V or 9V power supply

Place 555 timer IC on the bread board and make positive (+) and negative (-) voltage connections.

pin 1 = negative

pin 4,8 = positive

• Connect 100nF capacitor with pins 1 and 2
• Connect positive (anode) end of one diode with negative (cathode) of other diode and connect the common point with pin 7

• Place a 5k ohm potentiometer on breadboard and connect its middle pin with pin 6 and pin 2 of IC
• Also connect 1st and 3rd pin of potentiometer with the diodes common pin.

• Add a 1K ohm resistor b/w common pin of diode and positive pin of power supply and connect oscilloscope with pin 3 which is the output pin
• Connect led with pin 3 using 330 ohm resistor and by rotating the potentiometer we can see the change in brightness of LED and a variable signal on oscilloscope.
• To change the color of RGB we need 3 of these circuits because RGB has 3 diodes.

This circuit is created using the same method shown above. So by rotating these three potentiometers we can control the colors of the RGB led