The reference voltage created by diodes D5 and D6 is around 15.4V. One terminal is supplied with reference voltage, and the other terminal with some of the output voltage. This works by measuring the differential voltage on base terminals of T4 and T5. The voltage control circuitry is created from Transistors T4,T5 and T6. This is because they both have opposing thermal coefficients. The use of zener and a normal diode is to compensate for thermal drift of reference voltage generator. They both are driven by the reference voltage created by D5 and D6.

The second differential amplifier controls the output voltage. The first one being responsible for controlling the output current limiting. The power supply relies upon two differential amplifiers made out of Transistors T1 to T6. But in this circuit, the differential amplifiers have a negative power supply rail at (-3V), which can pull the output down to exactly zero. Most simple power supplies cant get the output to come down to exactly 0V or 0A. To cater that I have designed an adjustable 50V / 5A power supply with a variable output from 0V to 50V and adjustable current limiting from 0A to 5A.

Batteries, DC adapters can do fine job but as demand grows and project gets bigger a professional and adjustable power supply becomes a necessity. Out of all I would say power supply is most important since it powers up the projects. Every lab needs to be equipped with essential equipment.

Rangkaian power supply 5 volt 10 ampere