The last heavy downpour a weeks ago ruined the LEDs in my prototype back light because I hadn't waterproofed it (well it was supposed to be summer, as in sun, sun, more sun and only sun) so I ordered some new bright red LEDs from an eBay seller
here. I accidentally ordered 3mm instead of 5mm but they're just as bright so no worries.
I wanted to avoid using resistors as much as possible to make things easier to wire but I can't avoid using them for the red LEDs. The white LEDs are 3.4v max but running them at that level isn't good for them as they can get hot and burn out so I set the DC-DC output to 3.15v, so then to power the 1.9v red LEDs from that 3.15v I'm using a single 68 ohm resistor inline for each of the 4 I'm using.
Here's the whole wiring diagram of the project (simple, isn't it):
