| 摘要 |
PURPOSE:To provide the function of privacy call and transfer with a simple circuit by supplying a power supply of a sounding element from a telephone line in a master/slave telephone set where >=2 telephone sets are connected in parallel with two telephone lines and one control line. CONSTITUTION:When an operator of a telephone set TEL 1 hooks off a handset and the telephone line is closed, and when a pushbutton CK of an adaptor ADP1 is depressed, the telephone line constitutes a closed loop as L1-TL1-TEL1- TL2-CK-L3-L3 of ADP2-sounding body BZ-L2-telephone line. The sounding body BZ of the caller TEL1 is short-circuited by a CK and does not ring. Since a current flows to the sounding body BZ of the called telephone TEL2 through the telephone loop of the TEL1, the BZ of the TEL2 rings with a DC current from the telephone line. In hooking off the handset of the TEL2, the TEL1, TEL2 are connected to the telephone line and an ordering talking for transfer is attained between the TEL1 and TEL2. |
