| 摘要 |
PURPOSE:To omit a mechanical switch for application of power supply to a controller which controls the prescribed function of a telephone, by providing a pair of connection terminals for battery power supply to stop the feed to an intial setting circuit when the voltage of the battery power supply is lower than a working level and then to restart the feed when the voltage of the power supply is set at a level outside the working value. CONSTITUTION:When the voltage level of a battery power supply 6 is lowered, a charging power supply 7 is connected to the supply 6 via a diode 8 in the polarity shown in the diagram. Then the charging is carried out. When the supply 6 is charged up to the level of Zener voltage, the variable voltage is produced so that the voltage higher than the value VR necessary for initial resetting of a microcomputer 1 which controls the prescribed function of a telephone lasts for time tr needed for initial setting. At the same time, the initial resetting is carried out assuredly for the computer 1 since the battery voltage V5a+VBE (set within in a prescribed voltage range of the computer 1) is impressed to a power supply terminal 1V of the computer 1. |
