| 摘要 |
a hall sensor for generating a pulse signal by the rotation of an exhaust fan; an inverse amplifier for inverse-amplifying the output signal of the hall sensor and smoothing it by a condenser; a low-pass filter for filtering the output of the charging/discharging unit and then outputting it as a reference voltage; a reference voltage level adjusting part for lowering the reference voltage output; comparators for respectively receiving the output voltages of the inverse-amplifier and the amplifier to a non-inverse input terminal, receiving the output voltage of the low-pass filter, and comparing those signals; and a gas valve operation control for cutting off the operation control signal input of the gas valve operating unit when switching by to the outer wind entrance of the wind pressure switch.
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