The power supply is based on that project: LINK, although some new elements were added.
List of elements added:
transformer windings switch (so transformer emits less heat)
fan activating when the temperature of heat sink rises too much
separate system powering the operational amplifiers (That turned out to be necessary due to the transformer which has two switched windings. Another reason was that at the maximum output voltage and 3,2A load, voltage dropped. With stabilized power supply for the operational amplifiers, those problems were solved.)
new operational amplifiers for higher voltage +/-20V
milivoltmeter from AVT for accurate setting the output voltage
Some of those elements can be replaced with another, for example power transistors are 2SC2625, which usually are placed in computer power supplies. In the rear housing there is a mains socket, such as for computer power supply. Fuse and a silver grill are screwed to the heat sink.