| 摘要 |
PURPOSE:To alarm the shortage of ventilation by an alarm buzzer when the ventilating fan is not being operated with the maximum airflow amount by a method wherein an electric current detecting diode is connected in the strong operation circuit of the ventilating fan so as not to detect the operating condition except the strong operation. CONSTITUTION:When a gas instrument is used, a switch 1 is opened and the secondary side of a transformer relay 2 is opened, therefore, a contact 4 is closed and an electric source 3 is outputted in an output plug socket 5. When an illuminating switch 14 or a weak operation switch 16 is being put ON or either one of the switches is not being put ON, an electric current is not flowed through the current detecting diode 19, therefore, a voltage is not generated in both terminals of the diode, a current is not flowed through the base of a transistor 10 and the transistor is not operated. Accordingly, the current flows through a rectifying diode 11, a voltage dividing resistor 9 and a gate resistor 8, it also flows through the gate of the thyristor 7, therefore, the thyristor 7 is operated and the alarm buzzer 6 is sounded to alarm the shortage of ventilation. When a strong operation switch 18 is put ON, the current flows through the current detecting diode 19, the transistor 10 is operated and the sound of the buzzer is stopped.
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