| 摘要 |
A sound-responsive switching device comprises a transducer for generating a signal representative of sound intensity, a main operational amplifier with positive feedback provided by a parallel combination of a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and a switch for an external power circuit, the switch being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound. The device can have a different threshold for switching on than off. It is responsive to hand clapping and particularly suitable providing effects at dances, switching off reading lights at night, and the like. The device also responds to the touching of a metal surface, without mechanical motion or the production of noise. |
