| 摘要 |
PURPOSE:To operate an arbitrary time alarming device and check fault by connecting a temperature dependence resistor and alarm sensing switch in parallel and setting the resistor on or off. CONSTITUTION:The power supply 1, the main switch 2, the alarm lamp 3, and the alarm sensing switch 4 are connected in series and the temperature dependence resistor 12 with a positive temperature factor is connected to the alarm sensing switch 4. Consequently, when the alarm switch is off, current is applied to the alarm lamp 3 through the resistor 12. As time elapses, the resistance of the resistor 12 increases and the alarm lamp 3 turns off substantially. When the alarm switch is ?on, it always lights and notifies the fault. |
