This circuit was found in Radio Electronics from the 90s. The sensor is an oscillator whose frequency depends on humidity, an uncommon component nowadays.
The RCA integrated circuit used in this control is uncommon today. The circuit is from an...
We found this circuit in a Popular Electronics of the 90s. The circuit uses a touch sensor formed by...
We found this circuit in a European schematic from the 90s. The used integrated circuit can still...