| 摘要 |
PROBLEM TO BE SOLVED: To surely detect whether or not a main power supply battery is inserted to a holder in the radio calling receiver where a secondary battery output is supplied via a DC/DC converter. SOLUTION: Two positive terminals 2A, 2B electrically isolated when no battery 1 is inserted to a holder are provided. Then the positive terminal 2A is connected to a secondary battery 5 to be connected to an input side of a DC/DC converter 6 and the positive terminal 2B is connected to a battery detection terminal of a CPU 4. Through the construction above, when the battery 1 is extracted from the holder, since the positive terminal 2B is separated from the secondary battery 5, the absence of the battery 1 in the holder is surely recognized from a voltage of the positive terminal B. |
