This circuit from the 80's makes use of two transconductance operationals of the time. Modern equivalents can be used. The circuit does not need to be powered by a symmetrical source.
This stabilized source can supply currents up to 200 mA with the indicated transistor or 500 mA...
This circuit was obtained in a Popular Electronics of the 90s. The circuit is compatible with...
The 1: 1 transformer on this circuit found in a 1967 Electronics World can be wrapped around a...