so the circuit will have to regulate the current from 100mA-to-5A,
Using a 723, current limiting takes place when the voltage between pins 2 and 3 is 0.63 volts (or there abouts).
In this circuit, that voltage is developed across the 0.15ohm resistor.
At 4.2amp the voltage across the resistor is 0.63 volts.
At 18 amp the voltage across the resistor is 2.7 volts.
The current limit control, when set to one end of its travel, connects the resistor directly to pins 2 and 3. The current limit is 4.2 amp.
When the control is set to the other end of its travel, the voltage from the 0.15ohm resistor is divided from 2.7v to 0.66 volts. The current limit is 18 amp.
To have a current limit of 100mA, you will need to change the 0.15 ohm resistor to 6.2ohm.
However when 5 amp is flowing through this resistor, the voltage across it will be 31 volts, and the power dissipated will be 155watts, a bit excessive!
Using this circuit configuration, you current limits are not practical without switching the current sense resistor.
and voltage will be regulated from 2v-to-max available rectified voltage.
The output voltage cannot be adjusted to the maximum rectified voltage.
There must be some voltage across the 2N3055 pass transistor, so the maximum output will be a few volts less.
JimB