Stabilized power supply circuit with differential amplifier and over-current protection Part 2

The overcurrent protection circuit is composed of transistors VTa, VT4, detection resistor Ro, etc.
    This power supply cannot return to normal operating status after the overcurrent or short circuit fault is eliminated (because the VT3 conduction condition has not changed and the output
voltage is still zero). To reset, you must re-close or connect a reset button in series with the collector circuit of VTa.
    In the figure, the capacitor Cz acts as a delay when the power supply is turned on to ensure that VT4 is turned on first, thereby establishing the output voltage;
the function of the resistor Rs is to ensure that the adjustment tube VTi has an appropriate bias current.