We found this circuit in Radio Electronics from the 90s. The components are current. The sensor is a common general-purpose transistor. The connection to the sensor is made by twisted pair.
This circuit was found in a 1989 publication. The operational amplifier supports equivalents. The...
This humidity sensor indicates the different levels of conduction of the sensors through an LED...
Found in documentation from the 70s, this circuit uses components from that time. Some of these...