The circuit is based upon the μA723, a basic power regulator IC from the early 1970-ies. I boosted it with 4 2N3055 power transistors, mounted on 2 heat sinks piggybacked at the back to get a robust and reliable power supply that can deliver a lot of current without running too hot. The transformer is a 24V, 150 VA halogen transformer.
I built this device in 1982. At the time, I had access to a small metal workshop and I could made the chassis and case from sheet aluminium. The 1982 version had a single meter that could be switched between voltage and current. Originally, I built the control circuitry on a small piece of perfboard, the emitter resistors and driving transistor on a tagstrip, electrolytics fixed to the bottom.
I decided to give it two separate meters instead of a single one. I customised the dials by using letter transfers. It required some redesign of the front to accomodate two meters and three receptacles, but everything found a logical place. No place was left for a max-current control, but I didn't need that for this power supply. I made a new aluminium front plate to mask the large hole in the old front. Rubbed some letter transfers on it and covered it with a transparent coat. Instead of perfboard and mounting strips, I used a circuit board from an old 723 based computer power supply that could also hold the electrolytics. That looked a lot neater, though the circuitry was practically unchanged. Instead of passing the mains cord through a hole in the chassis, I used an IEC mains receptacle.
This resulted in a robust and very usable power supply, with a single disadvantage, that it cannot be set to 0 V. But I have other power supplies that can.