This circuit was found in an American documentation from the 80's. The sensor is a special integrated circuit, uncommon in our times. There are modern equivalents.
The operational amplifier 747 is old, no longer being used, but the configuration is valid for...
This circuit, from an American publication from 1971, generates a 25 Hz sinusoidal signal. Note...
In this circuit, from a 1977 publication, we have the traditional version of a filter tuned to 1...