DEVICE FOR CONNECTING A SUBSTITUTE CURRENT PATH IN CASE OF LINE BREAK
First Claim
Patent Images
1. In a system including at least first and second seriesconnected devices, each of said devices having at least one terminal and a line connecting said first device terminal with said second device terminal, the improvement which comprises DC circuit means for defining a normally closed DC circuit including said line and a ground path;
- first switch means for providing a pulsating current path between said first device terminal and ground when said DC circuit is opened by a break in said line; and
second switch means for providing a pulsating current path between ground and said second device terminal when said DC circuit is opened by a break in said line, said first and second switch means and said ground path providing an AC path between the first device terminal and said second device terminal when said line is broken.
0 Assignments
0 Petitions
Accused Products
Abstract
A system for providing a path between two series-connected devices should the line therebetween break including a bypass switch means for interconnecting the output of a first of said devices to the input of a second of said devices through ground upon such a break. The system is particularly adapted for application to central station alarm systems.
5 Citations
11 Claims
-
1. In a system including at least first and second seriesconnected devices, each of said devices having at least one terminal and a line connecting said first device terminal with said second device terminal, the improvement which comprises DC circuit means for defining a normally closed DC circuit including said line and a ground path;
- first switch means for providing a pulsating current path between said first device terminal and ground when said DC circuit is opened by a break in said line; and
second switch means for providing a pulsating current path between ground and said second device terminal when said DC circuit is opened by a break in said line, said first and second switch means and said ground path providing an AC path between the first device terminal and said second device terminal when said line is broken.
- first switch means for providing a pulsating current path between said first device terminal and ground when said DC circuit is opened by a break in said line; and
-
2. The combination of claim 1, and wherein said DC circuit means includes a source of DC potential and a voltage divider circuit having first and second portions.
-
3. The combination of claim 2, and wherein said source of DC potential and a first of said voltage divider portions are connected in parallel with said first switch means, said first switch means being adapted to provide said pulsating current path when the voltage across said DC source of potential and said first voltage divider portion rises above a predetermined level.
-
4. The combination of claim 3, and wherein said first switch means comprises a zener diode having a cathode connected to said first device terminal and an anode connected to ground.
-
5. The combination of claim 4, and wherein said second voltage divider portion is connected between said second device terminal and ground, said second switch means comprising diode means having its cathode connected to said second device terminal and its anode connected to ground.
-
6. The combination of claim 3, and wherein said first switch means includes first relay coil means connected between said first device terminal and ground and a first normally open contact means operated by said first relay coil means and connected between said first device terminal and ground.
-
7. The combination of claim 6, and wherein said second switch means includes second relay coil means and a second normally open contact means operated by said second relay coil means, said second normally open contact means, said second relay coil means and said second voltage divider portion all being connected in parallel between said second device terminal and ground.
-
8. The combination of claim 1, and wherein said first and second devices are AC coupled to said line.
-
9. In a signaling system including a central station, a plurality of remote stations, and a transmission line connecting said central station and said plurality of remote stations in series for the transmission of signals to said central station, each of said remote stations having a first and second terminal for connection to said transmission line, the improvement which comprises DC circuit means for defining a normally closed DC circuit including said line and a ground path;
- first switch means for providing an AC path between the second terminal of the first of each pair of adjacent remote stations and ground when said DC circuit is opened by a break in said line; and
second switch means for providing an AC path between ground and said first terminal of the second of each adjacent pair of remote devices when said DC circuit is opened by a break in said line, said First and second switch means and said ground path providing an AC path between said second terminal of the first of said pair of adjacent remote stations and said first terminal of the second of said pair of adjacent remote stations when said line is broken.
- first switch means for providing an AC path between the second terminal of the first of each pair of adjacent remote stations and ground when said DC circuit is opened by a break in said line; and
-
10. The combination of claim 9, and wherein said signalling system is a central station alarm system.
-
11. The combination of claim 9, and wherein said remote stations are AC coupled to said transmission line.
Specification