If you need a small bipolar low-voltage regulator that will fit in small boxes that are too small for the much bigger B-PS-1, or if you do not need a super audio-grade bipolar PS, like the B-PS-1, then the PS-12 is the solution, as many electronic circuits do not demand a high constant current draw. The double-sided PCB is extra thick (0.93in) and hold 2oz copper traces; it is 2.2in by 4.5in big and the heatsink is 1in tall; the main PS capacitors, 1 3/8in tall.
The PS-12's schematic shows how simple the circuit is. The parts used are fancy, not the circuit. An LM317 positive and LM337 negative regulator are used to establish the bipolar output voltages. It can deliver any voltage between +/-5V to +/-24V by selecting different values for resistors R3 & R4.
Kit includes a user guide and all the parts to populate the PCB, including the four hex standoffs, screws, and rubber O-rings, but not the power transformer.