A portable communication device has an electromechanical transducer for converting mechanical energy, caused by movements of the portable communication device, into electrical energy for supplying power to the portable communication device. The electromechanical transducer is arranged to store mechanical energy after a respective movement of the portable communication device ceases.

A timepiece comprising a generator (1) for generating a supply voltage of a first predetermined value U.sub.1, a barrel with a spring (5, 6), a winding mechanism (5') and a set of hands (7 to 9). The electronic circuit (11, 12) of the timepiece requires a minimum limited supply voltage having a second predetermined value U.sub.2. This circuit comprises a timebase (12) and a regulating circuit (11) for regulating the rotational speed of the generator. According to the invention, a voltage regulator (25) is connected between the generator and said electronic circuit for adjusting its output voltage to said limited second value U.sub.2. The ratio between the absolute value U.sub.1 of the predetermined first value U.sub.1 and the second predetermined value satisfies the relationship U.sub.1 =k.multidot.U.sub.2, k being a factor corresponding at least to the maximum expected variation rate of the absolute value U.sub.1 when the timepiece is worn.

The transmission device disclosed is inserted between a rotating oscillating weight and an electric micro-generator in order to drive the generator rotor from the oscillating weight by multiplying the rotational speed. Its intermediate wheel and pinion includes a barrel (27) whose central shaft (24) is coupled to the drum (41) of the barrel by a spiral spring (30). The inner end of the spring has a bent portion (34) which engages via resilience in any one of a number of hollows (51) in the shaft and can be released by sliding over a slanting side (52) when the shaft exerts too great a torque in the given rotational direction. This arrangement prevents damage resulting from shocks, in particular in the case of a watch, without using a friction system.

A starter which applies a mechanical rotating force to a rotor of an electromagnetic converter, such as a power generator, for startup of the rotor. The starter includes a startup spring (60) having an engaging portion (63) engageable with a 6th pinion (11a) of a wheel train coupled to the power generator. In interlock with the operation of pulling out a crown, a reset lever (70) is operated to bias the startup spring for engagement with the 6th pinion. Thereafter, the startup spring is released from the biased state in interlock with the operation of pushing in the crown. The startup spring is returned to the original position due to its own spring force, whereupon a mechanical rotating force is applied to the pinion. Since the rotating force can be set by a resilient force of only the startup spring, a stable rotating force is applied to the rotor (12).

In an electromagnetic converter comprising a rotor arranged by including a permanent magnet, a yoke disposed in the vicinity of the rotor for flowing magnetic flux and a coil wound around the yoke, at least a portion of the yoke is composed of an amorphous metal magnetic material. The amorphous metal magnetic material is a Co amorphous metal or a Fe amorphous metal. The electromagnetic converter is a small generator, a motor and the like. In an electronic timepiece provided with a generator device, the Co amorphous metal magnetic material is used for a first yoke (stator) and the Fe amorphous metal magnetic material is used for a second yoke (coil core). In an electronically-controlled mechanical watch, the Co amorphous metal magnetic material is used for a yoke. Portable electronic equipment is a timepiece provided with the electromagnetic converter, and so forth