Telephone line circuit

Details Telephone line circuit Telephone line circuit

H - Electricity

04

B

379/67

H04B 3/36 (2006.01) H04M 3/40 (2006.01)

Patent

CA 1105162

TELEPHONE LINE CIRCUIT Abstract of the Disclosure A transformerless bidirectional amplifier useful in a PBX4/2 wire line circuit, which blocks common mode signals and allows full control of signal levels, impedances, etc. The amp- lifier is comprised of a balanced tip and ring lead for connec- tion to a telephone set, and an unbalanced line output lead, first differential amplifier circuit having its input terminals connected through individual equal valued resistors to the tip and ring leads, the values of each of the resistors being at least 10 times the offhook impedance of the telephone set, a buffer amplifier having its input connected in a first circuit path to the output of the first differential amplifier circuit and its output connected in a second circuit path to a line out- put lead, and second differential amplifier circuit having its in- put terminals connected respectively in circuit paths to the first and second circuit paths. The output of the second differ- ential amplifier circuit is connected to one of the tip and ring leads and is also connected by a further resistors to the other input of the first differential amplifier circuit which is con- nected to the other of the tip or ring leads. The value of the further resistors is selected to apply sufficient output signal of the second differential amplifier circuit to the other input of the first differential amplifier circuit as to substantially cancel signal within the first differential amplifier circuit appearing at its input terminals from the one of the tip or ring lead from the output of the second differential amplifier cir- cuit.

296137

Affiliated with

Also associated with

Rating

Telephone line circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

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

Rate now

Comments { 0 }

Profile ID: LFCA-PAI-O-338740