Joined: Aug 2010
Posts: 12,760
Likes: 2,114
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
Back to the initial question, I think you are going to have to look for a transformer. I have looked for a transformer to boost 6vac up to 12vac but have not found one.
I would like to use such a transformer, a rectifier (about $2) and one of those cheap cigarette lighter USB chargers ($1 at the dollar store) to make a cheap USB charger that connects to a 6vac hub. I really do not want to pay over a hundred bucks for a USB charger that connects to a alternator hub when it should cost so little to build one with these simple parts. I am sure that the commercially made ones are better, but for occasional use I would like to have something like this.
If you find such a transformer, please let me know where to buy it.