| 摘要 |
PURPOSE:To check highly accurately a battery voltage by a single display element by comparing a reference voltage which is varied in plural stages and periodically, with the battery voltage, and varying a flickering period of the display element in accordance with the battery voltage is higher than which reference voltage. CONSTITUTION:The output of a pulse generating circuit 6 of about 8Hz turns on and off transistors 4, 5 through T type flip-flops 7, 8 and an AND gate 9; and the on and off period of the transistor 5 is selected to twice of that of the transistor 4, and also the ON-width is set to the same. Also, resistances R1, R2 and R3, R4 are set to 10kOMEGA and 1kOMEGA, respectively, a reference voltage (point A) of a comparing circuit 3 is set repeatedly to three kinds, that is, the transistor 4 is turned on, the transistor 4 is turned off and the transistor 5 is turned on, and both the transistors are turned off, and when a battery voltage Vcc is higher than 2.56V, a light emitting diode 1 is turned on continuously, and said diode is flickered at a period of 250ms when said voltage is lower than 2.56V and higher than 2.44V, flickered at a period of 500ms when it is between 2.44V and 2.35V, and is not flickered when it is <=2.35V.
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