Instead of farting about with a voltage regulator and a lighting coil, I came across a different idea for providing a taillight and headlight for Ratty. This idea also meshed with my want to not run wires all over hell and back. So, the idea of a simple 9-volt battery powered LED setup came about.
I have no idea why I started thinking of this option, but a quick google search led me (pun intended) to a source for LED lights intended for model railroad setups. Modeltrainsoftware.com offers dozens of options in the world of small LED lights. All sorts of colors, sizes, some that blink, and even the little snap-on adapters for 9v batteries. I was sold. I immediately ordered some 5mm cool white LED lights, which got me a free switched 9v adapter snap on thingy. Everything arrived the following day, thanks to their quick service and being located in Colorado.
My bounty of LED goodness from Modeltrainsoftware.com:
Individual 5mm LED lights. Red wire to +, black wire to -.
Snap-on 9v adapter that was included for free with ordering ten LED lights:
I also picked up a few more 9v battery adapters from Radioshack, and a spare on/off toggle switch. My ultimate goal is to have a setup housed in the headlight bucket, complete with battery, wiring, and the LED lights poking into the headlight reflector lens. That part proved very easy, as I just grouped about seven LED lights together, wired them to the adapter with the toggle switch inline, made a simple bracket for the battery to attach to.
I attached the LED lights to a fat washer with a bit of epoxy, then epoxied the washer into the back of the headlight housing:
Your favorite Canadian hippy screwing on the last mounting bolt:
It actually works!
I never intend to ride Ratty at night, and legally, I don't even need a headlight since the bike is pre 1979. But I figured a little bit of brightness out front when I ride will be good.
Then, I turned my attention to the taillight. I already had a simple trailer taillight mounted, so I needed to figure out how to make the LEDs work inside that small enclosure. It turned out to just be a matter of grouping the LEDs together, wrapping a bit of tape around their "stems" and giving them a quick dab of epoxy to keep them from flopping about. They fit right inside the housing.
I ran two wires down the bike through the stock wire routing locations, and attached them to the 9v battery adapter which is wired into the brake switch. No need for an on/off switch, as the brake switch does that.
Success! Quite a bright taillight.
Overall, I'm pretty happy with this little project.