A portable, miniaturized, self-contained audible alerting device is disclosed. The device is housed in a small case adapted to be positioned in a darkened enclosure, such as a medicine cabinet, for receiving light when the enclosure is opened, producing an audible signal after a predetermined time delay...http://www.google.fr/patents/US4255745?utm_source=gb-gplus-shareBrevet US4255745 - Apparatus for audible altering of enclosure opening
Apparatus for audible altering of enclosure opening
