 Wire bonder |
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| Dynamic random access memory device having an improved timing arrangement |
| Accordingly, it is an object of the present invention to provide a D-RAM device with an input/... |
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| Biasing scheme for FIFO memories |
| Accordingly, it is a general object of the present invention to provide an improved biasing circuit ... |
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| Air-deliverable, ice-penetrating sonobuoy |
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| Fiber optic alignment sleeve |
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| Connectors for optical fibers |
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| Circuitry for generating a sine wave and/or cosine wave from a pulse signal |
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| Single mode fiber-to-channel waveguide through-line coupler |
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| Remote control system |
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| Electronic telephone set |
| OF THE PREFERRED EMBODIMENTS In FIG. 1 is shown the transmission circuit 1 connected to a ... |
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Bridge lifter circuit
| Details |
Inventors: Brolin, Stephen J.;
Assignee: Bell Telephone Laboratories, Incorporated (Murray Hill, NJ)
Primary Examiner: Brigance; Gerald L.
Assistant Examiner:
Attorney, Agent or Firm: Nimtz; R. O.
The tip and ring leads (15,17) of a tip party transmission facility are reversed before connecting the separate channel units for the tip and ring party channels to bridge lifters (16,18) at the central office, thus permitting selective ringing. Tip party identification for billing is provided by a tip-party indicator (20) inserted in the tip party transmission path at the central office by grounding the tip conductor when needed. The need for rewiring the tip party telephone set is then eliminated by providing separate single party channel units. |
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DETAILED DESCRIPTION Referring to FIG.
1, there is shown a bridge lifter and tip party indicator circuit embodying the present invention.
Tip conductor 11 and ring conductor 13 of a shared line connect the central office equipment (not shown) with terminals 12 and 14, respectively.
Bridge lifters 16 and 18 connect the tip party leads 15,17 from the tip party carrier channel unit (not shown) and the ring party leads 19,21 from the ring party carrier channel unit (not shown) with the terminals 12,14, respectively.
Whereas the leads from bridge lifter 16 are shown reversed before their connection to terminals 12,14, it is equally possible for leads 15,17 to be reversed before their connection to bridge lifter 16 to achieve the same results which will be described hereinbelow.
By providing a high series impedance in the loop not in service, bridge lifters 16,18 ensure that only one of the two parties have access to line conductors 11,13 of the shared line and to a switching path through the central office at any given time.
That is, the use of bridge lifters 16 and 18 insures that only one of the two parties get service at any one time.
Bridge lifters may be made of saturable core reactors or of electronic components, known as miniature bridge lifters.
Saturable core reactor bridge lifters are disclosed in U.
S.
Pat.
No.
2,924,667 granted Feb.
9, 1960 to L.
Hochgraf.
Miniature bridge lifters are disclosed in U.
S.
Pat.
No.
4,166,931 granted Sept.
4, 1979 to W.
F.
MacPherson et al and U.
S.
Pat.
No.
3,881,068 granted Apr.
29, 1975 to C.
E.
Jones et al.
When single-party service is provided in conjunction with subscriber loop carrier systems, ringing signals to alert a called subscriber's telephone are detected at the COT channel unit by a ringing detector connected between the ring conductor and ground.
The ringing signals are than encoded and relayed to the RT channel unit for decoding and applying a remote ringing signal to the telephone ringers connected across tip and ring conductors of the loop
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I/O Systems 
