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 digitally programmed gain amplifier was obtained from Signetics documentation from the 1980s....
This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...