Abstract A ferrod sensor comprising an elongated ferrite stick having a pair of spaced apertures through which are threaded an interrogate winding and a read-out winding. Pulses or alternating current on the interrogate winding induce output pulses in the read-out winding as long as the ferrite stick is not saturated. A control winding is wound about the ferrite stick and is adapted to be energized by a pair of telephone lines, for example when the receiver is taken off the hook switch. This current causes saturation of the ferrite stick so that flux switching cannot take place and no pulses are induced in the read-out winding. The ferrite stick and its windings are placed within a ferromagnetic pot core thereby gaining higher sensitivity for the same amount of current as compared to known sensors as well as shielding from external magnetic fields. The device is very compact and a screw in one end of the pot core allows for varying the sensitivity of the device.
A ferromagnetic sensing device for monitoring the status of telephone lines comprising two ferrite half-cup cores, each having an end wall, an outer annular wall and an inner annular wall, the inner annular wall being shorter than the outer annular wall, said half-cups being joined end-to-end by their outer annular walls with their end walls facing outwards, an elongated ferrite element being disposed within said half-cup cores with its ends enclosed by said inner annular walls, said ferrite element having two apertures through which are threaded an interrogate winding and a read-out winding, a control winding adapted for connection across a pair of telephone lines being disposed within a space defined by the end walls and the outer and inner annular walls and encircling said inner annular walls and said ferrite element.
Claim 2
Dependent Claim
132 words
A ferromagnetic sensing device for monitoring the status of telephone lines comprising two ferrite half-cup cores, each having an end wall, an outer annular wall and an inner annular wall, the inner annular wall being shorter than the outer annular wall, said half-cups being joined end-to-end by their outer annular walls with their end walls facing outwards, an elongated ferrite element being disposed within said half-cup cores with its ends enclosed by said inner annular walls, said ferrite element having two apertures through which are threaded an interrogate winding and a read-out winding, a control winding adapted for connection across a pair of telephone lines being disposed within a space defined by the end walls and the outer and inner annular walls and encircling said inner annular walls and said ferrite element.
Claim 3
Dependent Claim
45 words
A device as claimed in claim 1 wherein a cylindrical piece of ferromagnetic material is disposed within the inner annular wall of one of said half-cup cores and said piece of material has a slot into which its an end of said elongated ferrite element.
Claim 4
Dependent Claim
82 words
A device as claimed in claim 1 wherein a cylindrical piece of ferromagnetic material is adjustably mounted within the inner annular wall of one of said half-cup cores for movement towards or away from an end of said elongated ferrite element, said half-cup cores forming a magnetic flux return path for flux produced in said ferrite element by said control winding and said flux return path having a reluctance which can be varied by movement of said cylindrical piece of ferromagnetic material.
Claim 5
Dependent Claim
41 words
A device as claimed in claim 3 wherein said cylindrical piece of ferromagnetic material has external screw threads engageable with internal screw threads on an annular ferromagnetic insert secured to the inner annular wall of said one of said half-cup cores.
Claim 6
Dependent Claim
35 words
A device as claimed in claim 3 wherein said cylindrical piece of ferromagnetic material has external screw threads engageable with internal screw threads on the inner annular wall of said one of said half-cup cores.