Charger for portable wireless devices that sounds by detecting the approach of a moving object using radio waves.

摘要

PROBLEM TO BE SOLVED: To provide a practical charger for a portable radio device in which a receiver therein including a speaker and a rechargeable battery gives an alarm for approximation of a weak radio wave source by ringing of the built-in speaker, in particular a charger that is devised for eliminating a device trouble like failing in giving a warning as much as possible.SOLUTION: A charger comprises means for ringing a built-in speaker or the like of a portable radio device on a test basis. In addition, it enables efficient check of ringing sensitivity by a test radio wave intensity of which varies periodically. The test radio wave may be a sine wave, a triangular wave, or a rectangular wave. By changing the intensity of radio wave periodically covering the weakest radio wave at which ringing barely occurs, a user can adjust sensitivity hearing intermittent ringing of "beep, blank, beep."