| 摘要 |
PURPOSE:To obtain an inexpensive and small long-term timer, by electrically detecting the abrupt voltage drop of a battery by setting the dry battery such as a silver oxide battery having a flat discharge curve to a time standard to perform an alarm or display. CONSTITUTION:A dry battery 1a is discharged through a resistor 1b. At first, a variable resistor 2c is regulated and a transistor 2b is set to an OFF-state. When the elapse of a time comes to To in a drawing, the voltage of the dry battery 1a is abruptly dropped and, therefore, the transistor 2b is turned ON and a transistor 2a is also turned ON to emit an alarm or to perform display by an alarm or display device 3b. The value of a capacitor or resistor 2d is selected so as not to generate voltage drop before a power source 3a comes to To. Because the discharge characteristics of the dry battery are used as a time standard as mentioned above, a timer used in a range from several months to several years can be easily realized.
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