ABSTRACT
Operational amplifiers with a small input current on the basis of field-effect or MOS transistors at the input are suitable for connecting the ceramic sensor to this type of circuit. The converting circuits with a frequency or a time output are produced on the basis of generator circuits to whose frequency dependent circuits the ceramic sensor is connected. The independence of the working modes of the heater and the thermistor offer wide possibilities of applying indirectly heated thermistors in various measurement circuits. Temperature sensors with a frequency output are widely used because of the possibility of a direct connection to a microprocessor system. Potential users of ceramic humidity sensors are the domestic air conditioners, microwave ovens, devices for preventing the irrigation point in videotape recorders, and some other domestic electrical appliances. Ceramic humidity sensors are applied in various devices, such as hygrometers, air conditioners, humidifiers, dehumidifiers, microwave ovens, etc.
