When I wired my boost gauge, I used the radioshack LED's, 5V @ 30ma. I used two in series, and assumed a 12V supply. Using an online calculator, I found that I needed a 68 ohm resistor. I ended up using 2 33 ohm resistors in series. The LED's only lasted about 6 months and went out. Reading through the ambient lighting thread, they used a single LED and a 470 ohm resistor. Doing the reverse math, this would mean they assumed an 18V supply. Is that right? What supply should I assume? Is the 18V just a safer supply to use for calculating the resistor?