The purpose of this circuit, which we found in the November 1986 Radio Electronics issue, is to determine the voltage across a zener diode. Several test currents can be selected.
The oscillator shown in the figure generates a rectangular signal with a 50% active cycle (square)...
This power supply can be implemented with a TIP32 providing an adjustable output at the 2k2...
This switched circuit was found in an old documentation and no information about the transformer...