Project: Universal Charger from Metro 2033, stuck on Motion Conversion

Sorry about the rather bland topic name.

So what I am talking about is, I was playing this awesome game called Metro 2033. It's about a post-apocalyptic world and all, and it features this really cool portable gadget called a 'Universal Charger'. We use it throughout the game to charge our flashlight, Night Vision Device battery and so on.

So I was thinking, supposing I was going hiking or something, and there were no electrical outlets around (kinda obvious, I am on the top of a hill), and I need my cellphone/flashlight/iPod charged. One solution is to lug separate batteries for the flashlight, the phone and the 'pod. But supposing I am gonna stick around for more than a couple days? I think having something like a 'Universal Charger' is a very good idea, especially in the hostel where we have frequent powercuts.

How it works has a really nice feel to it. Have a look:
Metro 2033 Charger - YouTube was kinda hoping to make this thing 😛 . As you can see, the gearing and the dynamo are obvious, it's the input that is a problem. There's that arm that you squeeze on, which somehow needs to be converted into circular motion. Keeping in mind that on the return stroke of the handle it needs to be free, what kinda mechanism shall I use?

What I've thought of:
1. ratchet-and-pinion-thingy: why is this a bad idea? not available readily in market => have to make it myself and needs to be made of metal => big problem

2. steal idea from how a clutch works: get a friction plate, which will be in contact with the other end of the handle when I squeeze it, but not so during handle return. sounds good, difficult to make 😔

so... kinda stuck there.