| 摘要 |
An alarm clock with coaxial digit wheels for one-minute, ten-minute and hour indications has a pair of contact-carrying disks, rotatable about the same axis, mechanically coupled with the 1-minute wheel and with the hour wheel, respectively, for entrainment thereby. Each disk confronts an associated selector drum bearing minute and hour indications, respectively, these disks being independently settable to display the time when the alarm is to ring. Each drum consists of insulating material and carries a terminal of an alarm circuit positioned to engage a contact near the periphery of the associated disk whenever the latter occupies a position corresponding to the selected drum setting; the disks are always conductively interconnected, by a contact spring on one disk engaging a metallic track on the other disk, so that the alarm circuit is completed when both disks occupy their preselected positions. With the digit wheels and the drums stepped intermittently, at 1-minute intervals in the case of the wheel of lowest denomination, the alarm circuit is reopened after a minute.
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