This circuit was found in an Electronics World of 1966. It has a range of 5 to 25 000 Hz at 1 dB and the diagram includes the power supply.
This traditional configuration can provide high voltages for an electric fence, for science...
We found this filter configuration in an old documentation. It is one of many possible ones that...
This circuit measures the conductivity of a saline solution, which is affected by the electrolysis effect....