Abstract: A combination audio and visual alarm system for selectively generating either audible, or visual, or combined audible and visual alarm signals, including a sound transducer device having a blocking capacitor connected thereto, a polarity-responsive electrical lamp, and a two-conductor circuit connected with the sound transducer device and with the lamp. In addition, there is a source of d. c. and a source of audio signals. A switch connects the two-conductor circuit to either the d.c. source or the audio source, thereby to enable simultaneous operation of the sound transducer and the lamp upon energization of the circuit by the source of audio, or to enable sole operation of the lamp when the circuit is energized by d.c.

Abstract: An emergency alarm system incorporating both signal generation and voice annunciation capabilities, for installation in a building or other structure. The system includes a standard fire alarm control panel and one or more loud speakers, each speaker having a series blocking capacitor. The panel has conventional supervisory circuitry and sensing/alarm terminals connected therewith, adapted to indicate an alarm condition when conditions warrant, as by signals received on multiple sensor lines that also communicate with the panel. A signal generator and amplifier are arranged to drive the speakers, under alarm conditions. There is provided a circuit-failure indicator including an electrical switch and an electro-responsive actuator device connected with the signal generator. The electro-responsive actuator device, when energized by the signal generator, maintains the switch in a closed-circuit condition.