Audio-detector alarm
US4170769A · kind A · utility
12Cited by
1References
11Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1978 |
| Grant date | Oct 9, 1979 |
| Priority date | — |
| Expiry date | Sep 6, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B3/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An intrusion alarm circuit including a single electroacoustical transducer, such as a diaphragm-supported piezoelectric element, connected to an amplifier in a positive feedback loop configuration. The transducer functions as both a sound pickup and sound generator. When the ambient sound level exceeds a preselected threshold level, the resulting vibration of the transducer generates a voltage which activates the amplifier, whereupon the transducer vibrations are sustained and amplified in the manner of an oscillator, thereby producing an audible alarm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.