Circuit knowledge

1.2V – 12V with regulated current limiter through resistors
Person see the website wants DC Volt adjustable Regulate 1.2V to 12V current 1-2A sizes at the first stage me think will choose the circuit that use IC LM317. But he tells have IC LM723 the many. Then of this circuit better which this easy circuit, use integrated number this circuit. And still use number transistor TIP41 0R TIP31 help enlarge current get about 1-2A fine VR1 for choose Volt follow want. The detail is other can see in the circuit has and original website http://www.elektroda.net/warsztatowe/zasilaczelabor.html

DC Power Supply Dual-rail Variable Circuit

* The circuit can be placed into the existing Variable DC Power Supply metal cabinet.

* Q1 and Q2 must be mounted on heatsinks. Usually, bolting them to the metal case (through insulating washers etc.) proved effective.

* The full ±15V output can be achieved only if the secondary winding of the supply Transformer used in the Variable DC Power Supply is rated at 48V minimum (center tapped).

* When using this circuit, please set the Current-limit control (P1) of the Variable DC Power Supply to any value comprised in the 50mA - 1A range but not higher.

* The second Op-amp (IC1B) contained in the LM358 chip was not used, but its input pins were tied to the negative supply and the output was left open.