| 摘要 |
PURPOSE:To provide a positive operation of timer circuit even under a low voltage of battery by a method wherein a timer operating winding is magnetically coupled to a transformer of DC-DC convertor, a rectifier circuit is connected to the winding so as to take out DC voltage higher than a voltage of battery applied as an input power supply. CONSTITUTION:A rectifier diode 19 connected to a timer driving winding 18 which is magnetically coupled to a transformer 5 of DC-DC convertor 1 constitutes a rectifying circuit together with a smoothing capacitor 20. DC voltage got from this rectifier circuit is required to be higher than a voltage of bettery 2 and so the timer driving winding 18 is wound with the number of windings required for fulfilling the condition. Thereby, a voltage supplied to the timer circuit 21 when the power supply switch 3 is closed again after the power supply switch 3 is opened once is set to become a value higher than the voltage of the battery 2 due to the presence of the timer driving winding 18, so that it is possible to have a fine accurate time of timer. |
