microuser . 1 2n3904 transistor with 1K resistor in series with base and connected to your favorite PIC pin. Transistor Emitter connected to ground. Transistor Collector connected to last cathode of 6 series connected LEDs. 47 Ohm Resistor in series with first Anode connection of LED string connected to 12 volts.

Dave Purola,
N8NTA