The first is a spring-controller circuit that exploits the fact that, although the spring provides energy at a fixed rate, a radio needs less power when it runs at low volume.

ECONOMIST: Clockwork technology

The spring is wound for half a minute, and then unwinds over six minutes, charging a battery in the process, and providing enough energy to run the radio for an hour. (This means the radio's spring-controller circuit is no longer necessary.) Thus, Freeplay has switched from making solely spring-powered devices to making battery-powered devices that are equipped with a clockwork mechanism for recharging and emergency use.

ECONOMIST: Clockwork technology

The controller's built-in adjustable spring-loaded clamp allows secure docking of any Android handset (including the Samsung Galaxy S3) or iPhone while sturdy soft rubber clasps protect handsets from being scratched or damaged.

ENGADGET: Gametel Bluetooth mobile controller lands stateside for $49.99