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Audio program switching apparatus

  • US 4,002,858 A
  • Filed: 12/19/1974
  • Issued: 01/11/1977
  • Est. Priority Date: 12/19/1974
  • Status: Expired due to Term
First Claim
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1. An electrical control apparatus, comprising a transducer converting electrical audio signals to audio sound waves, a primary source connected through a connecting circuit to said transducer and supplying a primary output including a continuous primary audio program, a secondary source connected to said transducer and selectively supplying a secondary output including a secondary audio program of a predetermined time duration followed by a control signal outside of the audio frequency range, an amplifying transistor connected in common emitter configuration and having a base circuit connected to receive said secondary output and a collector circuit operatively connected to a power source, a feedback coupling said collector and base circuits and including a first feedback path having a first resistor and a first circuit portion connected to a system ground potential through a first capacitor and a second feedback path having a second capacitor and a second circuit portion connected to said ground potential through a second resistor, said amplifying transistor resonating in response to said control signal to provide a resonating output at said collector circuit, a controlled rectifier having a gating circuit operatively connected to said collector circuit and an anode circuit providing an output in response to said resonating output, a timing circuit including a selectively variable impedance operatively connected to said power source and to a timing capacitor through a junction circuit connected to said anode output circuit, said timing circuit responding to said controlled rectifier and initiating a timing sequence of a predetermined time in response to said resonating output, a first switching circuit connected to said junction circuit and providing an output connected to said connecting circuit and operatively supplying said primary program to said transducer in response to said timing sequence initiation and operatively attenuating said primary program in response to the expiration of said predetermined time, and a second switching circuit connected to said first switching output and to said secondary source and operatively supplying said secondary output to said transducer and to said amplifying transistor in response to the expiration of said predetermined time.

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