This filter was found in Delco's 1965 documentation. It can be implemented with modern components according to the voltage and current to be regulated.
We found this circuit in the Radio Electronics magazine of January 1986. The frequency is given by the...
This circuit has a type of bias called "virtual earth" providing good gain, given by R2. The...
The figure shows how to convert a rectangular signal into a triangular signal using an integrator. The...