| 摘要 |
PROBLEM TO BE SOLVED: To supply a power from a post-equipment connected with a portable telephone set to the portable telephone set, and to always maintain a power necessary for the waiting or speech of the portable telephone set. SOLUTION: A hand free unit 13a connected with a portable telephone set 12 is provided with a diagnostic circuit 13c for diagnosing a power source circuit 12c in the portable telephone set 12, and a power supply circuit 13d operated in response to the diagnostic result of the diagnostic circuit 13c for supplying operating currents necessitated by a transmitting and receiving circuit 12b in the portable telephone set 12 to the power source circuit 12c. The power supply circuit 13d in the hand free unit 13 is used as the supply source of the operating currents to be consumed by the portable telephone set 12, and the current consumption of the incorporated battery of the portable telephone set 12 is reduced so that long term use can be realized. Also, wide application can be realized regardless of the model of the portable telephone set 12. |
