US3553674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Theft alarm system utilizing a bridge having a capacitive voltage divider
Assignee: ELECTRO Tech APPLIANCE SERVICE
•
Filing: 1968-10-31
•
Granted: 1971-01-05
•
Expires: 1988-10-31
Abstract
Abstract AN ALARM SYSTEM FOR INDICATING AN ALARM CONDITION AT ANY OF A NUMBER OF REMOTE POINTS, COMPRISES A PLURALITY OF ALARM CIRCUITS EACH INCLUDING A SOLID-STATE SWITCHING DEVICE WHICH IS TRIGGERED BY A CONTROL CURRENT APPLIED TO ITS CONTROL ELECTRODE IN ACCORDANCE WITH AN ALARM CONDITION. EACH CONTROL ELECTORDE IS CONNECTED TO A RESPECTIVE CAPACITOR CHAIN INCLUDING A CAPACITOR LOCATED AT THE RESPECTIVE REMOTE POINT, ANY TEMPERING WITH THE SAID CAPACITOR WILL AFFECT THE CHAIN SO THAT THE CONTROL ELECTRODE RECEIVES EITHER DIRECT CURRENT OR ALTERNATING CURRENT TO TRIGGER THE SWITCHING DEVICE.
Inventors
- 👤 William John Head
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:35
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/02; G08B29/04; G08B29/046; G08B13/00; G08B13/22; G08B29/06; G08B29/08
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |