This old circuit, from the 80s, was found in American documentation. The circuit uses dual gate FETs (MOSFETs) and has no data on the coils used.
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...