Door activated burglar alarm utilizing time delay
US4276545A · kind A · utility
4Cited by
7References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1979 |
| Grant date | Jun 30, 1981 |
| Priority date | — |
| Expiry date | Sep 24, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/181
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A door-activated burglar alarm incorporates a firing capacitor that is charged by a battery during the quiescent state of the alarm. The firing capacitor will provide an additional current to fire a buzzer when the alarm is triggered, even if the battery is weak. (Less current is needed to maintain the buzzer, once it is fired). One embodiment provides exit and entry delays.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.