PURPOSE: To reduce the number of cores of a wiring cable by providing a level adjusting circuit and a noise eliminating circuit between a filter circuit of a key telephone set and a receiving circuit to superimpose an information signal on a channel.
CONSTITUTION: In a receiving stabilizing circuit of a key telephone set, an information signal extracted by an information band signal filter 14 is amplified by an amplifier 10a, a noise component is eliminated through a noise eleiminating circuit 10c comprising diodes and only a signal component exceeding the operating level of the diode is outputted to a receiving circuit 8. Further, a level adjusting circuit 10b is inserted between the amplifier 10a and the noise eliminating circuit 10c, and an excessive signal outputted from the amplifier 10a is limited to protect the receiving circuit, and the transmission of a prescribed level to the receiving circuit is enabled.
DOI AKIO
SANEYOSHI NORIO
| JPS5691566A | 1981-07-24 | |||
| JPS5681220A | 1981-07-03 | |||
| JPS544516A | 1979-01-13 |