Driving a Tri-Color LED
This circuit drives each color slowly from dark to full brightness. Each oscillator has a different frequency. This creates a total mixture of colors and allows the RGB LED to produce all its different colors. Change the 220k/8.2k etc. for each oscillator to get a different mixing effect.
The output pin 3 goes high immediately, but the base is slowly taken high because the 100u takes time to charge via the 8.2 K etc. resistor.
