This signal conditioner humidity sensor was found in a 1980s Linear Technology documentation. The circuit uses components from the era that can be designed with modern equivalents.
This circuit was obtained in an American publication from the 70s. The instrument is 100 uA, and...
We found this circuit in an English publication from 1980, but it can be assembled with BC548...
This circuit with a component from the time was found in the Radio Electronics magazine of...