Allows a 4 pin common cathode RGB LED to be controlled via a single Analog in (and a 5V mains). This is feasible because there are constrained color targets:
0.0 V = Blue
5.0 V = Red
The bottom voltage source is a GPIO pin. An AC voltage source is used to simulate the range of possible voltages achievable with PWM.
NOTE: Given my previous struggles in getting the green LED to light (see http://everycircuit.com/circuit/6552346996244480 ) I modified the circuit to utilize only two LEDs (since only blue and red are required for my purposes). A physical implementation of this has not yet been attempted but it shall also use the 2N3906 Transistors and the same common cathode RGB LED (operating voltages: 2V, 3.2V, 3.2V).
