As mentioned previously, I felt a need to over-complicate my nice, simple, and reliable SON dynamo lighting system with a handlebar-mounted three-position switch. The concept was simple; center position == off, other two positions correspond to primary (LED) headlamp only and primary + secondary (halogen) lamps. The execution, well, let's just say that A) it's a prototype and B) I still have some strategic work to do with heat-shrink tubing and sealant of varying forms.
Pictures(please excuse quality: rushed lunchtime camera phone shots are not my forte)
Note lack of bulb in front view. Silly-looking, eh? Cries out for something to fill the aching void.
Extra quick-connects at the hub, so I can readily rewire the lights directly to the hub if necessary
I ended up cannibalizing an old Schwinn halogen handlebar light for the main housing; pulled out all of the guts, and did some drilling and filing to get an el cheapo SPDT center-off switch to fit nicely. JB Weld-ed a two-position barrier block inside, just so I didn't have to twist all the wires together, and did up a bunch of connectors using 18ga speaker wire and standard 1/4" quick-connect terminals. I was clever enough to wire it such that, if needs must, I can throw in a little 2" jumper cable and cut the switch out of the system completely, effectively going back to the original wiring plan if the switch barfs.
I still need to do some weather-resistance work on most of the joins, and may well throw some dielectric grease in all the contact points while I'm at it.
It's ugly as sin; the old Schwinn light is huge, and having the empty reflector in front just looks silly; I'll probably throw in a blinking "be-seen" LED at some point. For that matter, I'm giving thought to attaching a LED reading light to the housing as well, for cue sheet perusal in darkness.
Long term, I'd like to fabricate up something more polished, maybe design it in kit form so that it can be readily added to an off-the-shelf dynamo system.