High-output LEDs are available in a wide variety of colors, including variants of red, green and blue within a single package. By varying the intensities or each LED, numerous colors can be created and even "faded" continuously through the full spectrum. The usual technique utilizes pulse width modulation (PWM) to control the intensity of the red, green and blue LEDs by means of a microcontroller. Multiple channels require specialized driver chips or coding PWM in software. The latter approach is demanding of the CPU, especially when controlling more than a few channels, and a more efficient algorithm known as bit amplitude modulation was used here.
A PIC 12F683 or 12F629 drives the RGB Piranha-like LED. Also visible is the Vishay IR receiver module (on the left) for remote control of color choice, fade/jump speed, etc. using a TV remote control. A translucent plastic box in the shape of a chinese food takeout container made an interesting enclosure.