Humidity sensor alarm unit

Abstract From the Canadian patent

An alarm unit for a humidity sensor activates an alarm circuit when the relative humidity rises above a certain value or under certain malfunction conditions such as a missing sensor or a cut cable, includes a first circuit for establishing a reference signal, and a second circuit adapted to be connected to a humidity sensor for responding thereto and for generating a humidity out-of-limits signal. A third circuit responds to the reference signal and to the humidity out-of-limits signal to generate an alarm signal. The third circuit includes a level detector, and the first circuit comprises an impedance device which cooperates with the second circuit which in turn connects the sensor to the …