Abstract: In a vibration motor assembly for use in, e.g., a portable phone, a weight is mounted on the output shaft of a motor and has a hermetically closed bore filled with a magnetic fluid. A magnetic body is disposed in the bore in the vicinity of the center of rotation of the weight. When the motor is not energized, the weight is held in a halt together with the shaft of the motor. In this condition, magnetic particles included in the magnetic fluid adhere to the magnetic body due to a magnetic force acting between the particles and the body. That is, all the magnetic particles are positioned in the vicinity of the center of rotation of the weight. Consequently, even a small torque, i.e., a small current can cause the motor to start rotating.

Abstract: A selective calling receiver comprises two separate bands having an antenna circuit for tuning incorporated therein. The first band has a first antenna and tuning capacitors incorporated therein and stoppers formed and arrayed on the outer surface thereof. Predetermined points are provided to the first antenna, providing different effective antenna lengths, respectively. The respective stoppers are provided with electrodes which are connected to the predetermined points of the first antenna through the tuning capacitors, respectively. The second band has a second antenna and a hook. The hook can be engaged with a selected one of the stoppers of the first band depending on the user's wrist thickness. The hook comprises a conductor electrically connected to the second antenna. When engaged with a selected one of the stoppers, the hook brings into electrical contact with the corresponding electrode to form the antenna circuit.

Abstract: A personal radio paging receiver includes a radio section, a control section, a DC/DC converter, and a secondary battery. The radio section receives/demodulates an external radio signal and outputs a POCSAG signal. The control section divides the POCSAG signal into a first sync signal portion and a second batch signal portion, and outputs a control signal during a period of the first portion. The DC/DC converter operates for only a period during which the control signal is received. The secondary battery supplies power to the control section in synchronism with the second portion. The DC/DC converter is supplied to charge the second battery.