UK consumers should be able to buy a clockwork mobile phone charger by the end of 2001. The device will allow mobile users to use their phone even if the battery has run flat. It consists of a small hand crank attached to a dynamo. Turning the crank generates mechanical energy, which is converted to electrical energy within the charger and then stored on a small battery. Freeplay, the company that designed the device, claims that turning the crank for 30 seconds will generate enough power for a six-minute phone call. It has teamed up with US mobile giant Motorola, who will help to market the charger, expected to retail at around £45. The charger has been designed to match Motorola's product range, but according to reports it should work with most mobile phones. According to the New Scientist, a simpler version of the charger could be used in the developing world. Freeplay is the company that successfully turned the clockwork radio designed by British inventor Trevor Baylis into a commercially successful product. There is one obvious problem with the handheld charger, though. Because turning the crank causes charge to be stored on its internal battery, the mobile phone must be plugged into the charger while the call takes place. It is not possible to recharge the phone's own internal battery. Back in early 2000, Trevor Baylis claimed to be working on technology that would allow a user to charge a mobile phone by walking. One idea involved fitting piezoelectric materials into the sole of a shoe, which would spark electricity if they are bent or compressed. Another was to fit a dynamo into the shoe, which would spin every time the heel hit the ground. A start-up -- The Electric Shoe Company -- was set up to develop these ideas, but no products have come to market, yet. An American company is also developing hand-powered charging devices. AladdinPower already sells a hand-powered charger for generators or batteries, and is planning to begin selling a foot-powered device that would recharge laptops, mobile phones and video camera by October 2001. See the Mobile Technology News Section for full coverage. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Telecoms forum. Let the editors know what you think in the Mailroom. And read other letters.