From my point of view one of the best ways to get started in electronics is to build your own laboratory power supply. In this instructable I have tried to collect l7812cv voltage regulator pdf the necessary steps so that anyone can construct his own.
All the parts of the assembly are directly orderable in digikey, ebay, amazon or aliexpress except the meter circuit. I made a custom meter circuit shield for Arduino able to measure up to 36V – 4A, with a resolution of 10mV – 1mA that can be used for other projects also. The power supply has the following features: Nominal Voltage: 24V. The document describes all the functional parts, icluding the ordering link, of the bench power supply and how to connect them.
Cables, in general use scrap cables you have in house. 600V in USA, 750V in Europe. The power supply board has been modified to obtain 12V instead of 24V. The positive pin of the CC LED from the power supply circuit is wired to the mode connector of the Meter Circuit.
This allow it to know when to display CC or CV mode. One sets the OV threshold and the other sets the OC threshold. These potentiometers do not need to be multiturn, I have used the original potentiometers from the power supply circuit. It shows the present information about output voltage, output current, OV setpoint, OC setpoint and status.