PHONE EXCHANGE SET Russian patent published in 1996 - IPC

FIELD: communication devices. SUBSTANCE: device has switching unit 1, telephone line terminals 2, pulse-controlled gate 3, first and second diode bridges 4 and 16, voice gate 6, first, second and third diodes 7, 9, and 29, resistor 8, keypad 10, control unit 11, current stabilizer 12, voltage stabilizer 13, first, second, third, fourth and fifth capacitors 14, 15, 17, 20 and 30, OR gate 18, calling relay 19, calling relay contact 21, amplifier 2, AND gate 23, counter 24, detection unit 25, oscillator 26, power amplifier 27, sweeping frequency oscillator 28. Device provides possibility to connect several phone sets to single line. EFFECT: increased capacity of phone exchange office. 2 dwg