Originally Posted by mswantak

You've got a late-'60s German-made Union dynamo light set -- the best you could buy then, and still darned good (although the later voltage-regulated Union dynos prevented popping bulbs on steep downhills). I've got Union dyno sets on all four of the bikes my wife and I ride regularly, and I'll go to bat for them anyday -- trouble free, and good light output. None of my local LBS's stock the bulbs anymore, and I've horsed around trying to substitute bulbs from Radio Shack and other contemporary sources with limited success. In a pinch, a bulb from a four-battery flashlight (4 X 1.5V = 6V) can work, but better to just order some bulbs from either of these sources:

http://www.reflectalite.com/lightmodel.html

http://www.thethirdhand.com/index.cg...d=749279623590

Dyno light sets can occasionally be irritating to set up the first time, and can have mystifying troubles but I've found that it's almost always a grounding problem, especially on lightweights with alloy components. The stock installations assume having a good ground at the point where the headlamp or tail lamp mount; usually the tail lamp mounts to the same bracket as the dyno, so that's generally okay. The headlamp however, can be a fussy bugger -- I had one that couldn't ground through the grease in the headset bearings. Alloy stems are another regular impediment to a good circuit.

After much wailing and gnashing of teeth, I've arrived at using duplex wiring on my installations (like stereo speaker cable -- two wires moulded together). That way I can use the second wire as a negative and run it back to a common ground at the dyno mounting bracket. An added benifit is that speaker wire can be found in a number of colors to better match the frame color.

Another nice period-correct addition to a dyno light set is a Soubitez Steady Light; it's a small battery-powered module that you wire between the dyno and lights that keeps the lamps powered up for 30 seconds whenever the dyno stops. I bought one for my Raleigh and it works like a charm. There's a guy on eBay that usually has them available.