Approximately how much energy can be generated from a portable hand-crank device?

Question

I've seen a few kinds of emergency radios (like the ones that NPR stations give away during pledge drives).. and I was wondering how much energy could be generated by hand operated devices? Do radio have such low power requirements that hand cranks are convenient? Or can other devices be used with hand cranks.. and if so, what kind of devices..? Not laptops, but.. phones? not (really) flashlights, but maybe simple calculators?

Answer 1

This model can generate up to 10V and 300 mA

http://scientificsonline.com/product.asp?pn=3038029&bhcd2=1174201504

You can also make your own!
http://www.creative-science.org.uk/gen1.html

Answer 2

You can't generate much power from a hand operated crank, especially over the long term. But a portable radio doesn't have to draw much power. It may seem surprising, but a 1/4 watt speaker can deliver quite a bit of sound. An LED type of flashlight doesn't draw a lot of power, either. Both of these devices can be powered easily with a hand crank. I have seen both that use a hand crank to wind up a spring which keeps power going so you don't have to continuously crank.

If you want more power, you could use a bicycle to run a generator. Your legs are stronger than your arms. Sitll, it takes a lot of leg power to keep a 100 watt light going. Most people could only do that for a few minutes. It would be hard to keep something like a laptop going for any length of time.