| 摘要 |
An automated and seemingly animated door knocker is disclosed that includes a housing with a pivotably connected knocking member, the housing being releasably supported on the door by an over-the-door hanger or other similarly satisfactory attachment device, and the knocking member being reciprocated by a battery-powered, motor-driven linkage that is controlled by an integrated circuit and activated by a difference in light intensity as sensed by a photocell when someone approaches the door. A sound generator controlled from the circuit board is also desirably activated contemporaneously with the motor-driven linkage to play a prerecorded sound sequence.
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