Opto acoustic alarm clock, has electronic circuit connected to service network twenty minutes before set waking time by internal mechanical contact

摘要

The clock has an electronic circuit connected to a service network twenty minutes before the set waking time by an internal mechanical contact. A lamp is switched on, and with the circuit a second lamp is switched on five minutes later. Two further lamps are illuminated and after the fourth lamp is illuminated, a time of five minutes passes before an acoustic tone is triggered.