This power supply will give you fixed regulated output at 5V, 6V, 9V and 12V, while the 18V output is unregulated. You could add some regulated IC like LM7815 or 7818 if you need higher output voltage.
The supply can be used for supply output voltages from 1 to 35V. The line transformer should be selected to give about 1.4 times the desired output voltage from the positif side of filted capacitor C1 to ground. Potensiometer R2 sets the output voltage to the desired value by adjusting the reference input. Rsc is the current limit set resistor.
For example, if the maximum current output is to be 1A, Rsc=0.65/1.0 = 0.65 Ohm. The 1KOhm resistor,R5, is a light-loaded resistor designed to improve the no-load stability of the supply.
The charger's output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-connected cells up to a maximum of 18V.
Power transistors Q1 and Q2 are connected as series regulators to control the battery charger's output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10.