Electronic monitoring system with short-circuit protection
US3932774A · kind A · utility
Inventor
Key dates
| Filing date | Jun 24, 1974 |
| Grant date | Jan 13, 1976 |
| Priority date | — |
| Expiry date | Jun 24, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/0824
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A contactless motion detector, including an oscillator and an amplifier, has an energizing circuit connected across a Zener diode in a section of a voltage divider also comprising a current-sensing resistor, another section of this divider comprising an output thyristor in parallel with a resistive branch which may be a constant-current unit. The voltage divider receives pulsating direct current from a supply circuit including a load; an ancillary thyristor has its gate and cathode connected across the current-sensing resistor so as to fire when the load current exceeds a certain limit, the two thyristors being so coupled to each other that conduction of the ancillary thyristor cuts off the output thyristor. Normally, the output thyristor is controlled by a switching transistor responding to an output signal from the motion detector; the ancillary thyristor, when conducting, may directly lower the gate potential of the output thyristor or may remove normal operating potential from a deactivating input of the detector to disable a switching transistor which controls the output thyristor in response to an output signal from the detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.