Those Sanyo dynamo are cool. I have one i've had since 1982 and I loved it until it... failed. Bearings started screaming bloody murder and not generating any power. I got a NOS replacement, and it... failed. Same way. I got... eh. Long story short, I now have four or five of them, and they are all inoperable. I won't be trying again. Anyone want one? Make me an offer.

I have a couple Soubitez ones that are less elegant but seem better lubricated. I've used one for a year or two with no problems...

In principle I think these are a good idea, but the Sanyo ones did not work out.