This detector with ultra-low deviation was found in an American documentation from the 90s. Operational amplifiers are from that time. The power supply must be symmetrical.
This circuit provides a symmetrical voltage of 15 V output from the 6.3 V secondary of a small...
We found this circuit in an American 1980s documentation. The operational ones used are not common...
This transistor source can supply currents up to 2 A and the voltage determined by the zener...