As a student I built this circuit in 1982 from a circuit diagram I found in an electronic magazine at the time. Built it as a dual supply unit with analog panel meters, modified a small bit to incorporate different reference resistors to o offer current ranges to 100ma, 1A and 3A with an SCR added for current cut-out option. Has been using up till now (more than 30 years) on my workbench. Still think it's an excellent power supply. I will now re-build and construct it more professionally. So glad I found the circuit again and the upgrades on this forum.