HOLD CIRCUIT FOR MULTI-LINE KEY TELEPHONE SYSTEM

• Main Authors: YOOK A,CA, LEE F,CA
• Format: Patent
• Language: English
• Published: 15.05.1973
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TELEPHONIC COMMUNICATION

A multi-line key telephone system comprising a plurality of telephone stations each of which has access to a plurality of telephone lines. Individual line-holding circuits are provided, which are connected to or connectable with any one of the individual line circuits and any one of the individual telephone station circuits. Each holding circuit has a resistive coil in series with a reed switch with an equivalent resistance exceeding the resistance of any one telephone station circuit. In parallel to the reed switch in each holding circuit is a circuit path which goes through the respective telephone line key, a common hold key, and the hook switch. In each station operation of the hook switch and depression of a selected line key connects the telephone circuit to a selected telephone line. Subsequently operation of the common hold key electrically completes the said circuit path and so shorts the reed switch, releases the said line key, and then energizes the coil to lock the holding circuit across the said telephone line. Further connection of any telephone circuit to the telephone line sufficiently de-energizes the coil to release the reed switch and disconnect the holding circuit from the telephone line.