System for controlling an electronic warning device
US4232305A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1978 |
| Grant date | Nov 4, 1980 |
| Priority date | — |
| Expiry date | Dec 18, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B3/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The invention relates to electronic warning devices. The control system includes means for supplying an accurate clock signal and a divider (CD1, CD2) for dividing the clock signal to obtain an audio frequency, adjusting the mark/space ratio of the audio frequency for application to a power transistor (T6), said transistor driving a loudspeaker (HP), providing a cyclic modulation for modulating the clock frequency; and timing the duration of the sound emission of the loud speaker. The timing functions can all be provided without the use of electrolytic capacitors as would otherwise have been necessary, thereby avoiding problems due to the lack of precision and drift in the values of such capacitors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.