“This is a laboratory power supply with a stabilized output, continuously adjustable from 0 to 20VDC and from 2mA to 4A. The current limiter makes it useful in experimenting with electronics because you can limit the maximum current before applying the voltage. This power supply has also build-in protections from parts failure and output overload.This is a modified circuit initially found at www.electronic-lab.com. This circuit can also be found as a commercial DIY kit, or module, and is very popular. Simulations in on this were performed in EveryCircuit and schematic drawings are exported from EasyEDA. Both of these programs are web based and free.You can also checkout my website Skalamerie for this instructable, but basically you can find the same things as here.”