Key telephone system

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

179 15BB, H04Q 518

Patent

active

041840542

ABSTRACT:
A key telephone system is provided which comprises: a plurality of key telephones; a key service unit; a plurality of transmission paths each including a first transmission cable for transmitting a voice signal between the key telephone and key service unit, a second transmission cable for transmitting a first control signal from the key telephone to the key service unit, and a third transmission cable for transmitting a second control signal from the key service unit to the key telephone; first, second and third transformers of which the primary windings are connected to the key telephone and the secondary windings to the first, second and third transmission cables; and fourth, fifth and sixth transformers of which the primary windings are coupled with the first, second and third transmission cables, respectively, and the secondary windings to the key service unit. The key telephone system is further provided with a seventh transformer of which the primary winding is connected to the key telephone, and the secondary winding between the center taps of the secondary windings of the first and second transformers and an eighth transformer of which the primary winding is connected between the center taps of the secondary windings of the fourth and fifth transformers and the secondary winding to the key service unit.

REFERENCES:
patent: 3604857 (1971-09-01), Opferman
patent: 3843845 (1974-10-01), Ridley
patent: 3973085 (1976-08-01), Shiff
patent: 3975594 (1976-08-01), Guntersdorfer
patent: 4046972 (1977-09-01), Huizinga et al.
patent: 4061887 (1977-12-01), Kasson et al.
patent: 4092501 (1978-05-01), Suzuki et al.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Key telephone system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Key telephone system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Key telephone system will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-1029161

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.