| 摘要 |
PURPOSE:To inform a drop state of a voltage of a DC power source by operating a free running multivibrator by a transistor (TR) which has connected a Zener diode to the base, and flickering a light emitting element. CONSTITUTION:When a voltage of a DC power source 5 is high enough, a Zener diode 1 is turned on, and a switch TR2 is turned on. Therefore, the collector of the switch TR2 becomes about ''0''V, and a free running multivibrator 3 does not oscillate, therefore, a light emitting diode 4 does not flicker. Subsequently, when the voltage of the DC power source 5 drops gradually, and approaches the sum or below of the base-emitter voltage by which the Zener diode 1 and the switch TR2 are turned off, the Zener diode 1 becomes a cut-off, the switch TR2 is turned off,and the collector rises to the voltage of the DC power source 5. Therefore, the free running multivibrator 3 starts its oscillation, and the light emitting diode 4 flickers. |
