GB1420603A - Audible warning devices - Google Patents

Abstract

1420603 Selective signalling J ROSE and H SMALL 13 Dec 1972 [8 April 1972] 16325/72 Heading G4H An audible warning device has a plurality of inputs, with holding means, to cause playback of respective audio recordings made on an audio recording medium, simultaneous inputs being resolved according to a predetermined priority order. An alarm condition producing a negative potential at any of input terminals 1 energizes a respective relay 2 (latched via contacts 3), a respective lamp 6, and a common relay 7 (latched via contacts 8). Contacts 9 of relay 7 energize a drive motor 10 and amplifier 11 of a magnetic tape loop playback system, contacts 4 of the energized relay 2 selecting a corresponding read head 12 on a respective track of the tape to feed the amplifier 11 which drives one or more loudspeakers to deliver a verbal statement of the nature and/or location of the condition &c. If more than one relay 2 is energized, only the first in a rank order is effective to control the loudspeaker, due to the series interconnection shown of the contacts 4. A photodetector 16 detects a hole in the tape after one rev. to energize a relay 13, de-energizing relays 2 via contacts 14, and the latching circuit of relay 7 via contacts 15, thus stopping the playback (or this may be done in response to an operator action or after a counted predetermined number of playbacks or after a predetermined time). The input from 1 can be disabled by a push-button 5 acting at 18 but it also acts at 17 to connect lamp 6 to a flasher 19. A button 20 prevents an input 1 from producing playback, but lamp 6 is still lit, and in addition a lamp 21 is flashed on and off while button 20 is actuated. Possible alarm conditions are smoke or machine breakdown in a factory, or pressure, or imminent or actual shortage of fuel, oil, coolant &c. in a car or other vehicle. Instead of a magnetic tape, a mechanical or optical storage medium may be used. Instead of being on different tracks, the messages may be superimposed, using different frequencies. The amplifier 11 may feed an intercom or telephone. Transistors may replace the relays. Manual actuation of inputs 1 may be possible, e.g. for testing. Actuation of an input 1 may also produce machine-switch-off.