Provided is a portable, thermoelectrically powered device, such as a flashlight or headlamp. The device comprises at least one thermoelectric generator for extracting body heat from a user, the Thermoelectric generator located on and extending through an elongated open ended outer shell, a heat sink in contact with an inner surface of the thermoelectric generator and configured to provide an elongated first cooling channel therethrough, circuitry in electrical communication with the thermoelectric generator, the circuitry comprising a transistor oscillator, a step-up transformer and a decoupling capacitor, the circuitry in electrical communication with a power sink, such that in use, a temperature gradient across the thermoelectric generator is sufficient to result in generation of at least about 25 μW of power.