Wind up gadgets are typically silly because they require a lot of work for a little output - usually more than the average person is willing to put in. However, there are some ideas that still deserve a nod. Such is the Piranha Dynamo shaver.
The Piranha’s Lithium Ion battery is recharged by winding it up. So say you're camping and want to groom while off grid. You're already on a roll from winding up your LED camping light, so you just wind, wind, wind, and shave away. It does have an AC charger, if you don’t feel like putting out the effort, but why bother – it’s a great excuse for a mini morning workout.
It offers a pretty fair input-output trade off, too. About one minute of winding yields about 1.2 minutes of shaving. If the battery is fully charged, you get a little over 60 minutes of shave time. Not too shabby.
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