| 摘要 |
PURPOSE:To exchange a built-in battery so as to enable a radio telephone system to correspond to various specifications by constituting the title system so that the rated currents of the built-in different batteries are detected automatically and a charging current in a charging circuit can be set to be the charging current corresponding to the rated current according to the detected rated current. CONSTITUTION:When an external power source 51 is connected to an external power source terminal 5, a power source switching circuit 4 switches a radio telephone circuit 1 from the built-in battery 2 to the external power source 51. At that time, the charging circuit 3 charges the internal battery 2 by using the power of the external power source 51. In the case that the built-in battery 2 is of the rated capacity of 2AH, since the impedance of its detection terminal 22 comes open, the transistor 61 of a detection control circuit 6 comes to be an ON-state, and a relay contact 65b is switched to a 2AH charging part 31, and the built-in battery 2 is charged favorably by the 2AH charging part 31. Besides, in the case of the built-in battery of 4AH, the impedance of its detection terminal 22 comes short, the transistor 61 comes to OFF, and the relay contact 65b is switched to a 4AH charging part 32, and the built-in battery is charged favorably by the 4AH charging part 32. |
