Learn about many Electronics components datasheets with their pinout details, uses, the example circuits, and how to use them.
Small appliances have microcomputer that requires 5V power supply. Why it can use only 1.5V battery? The 1.5V to 5V boost converter circuit inside them.
See 5V 3A power supply circuit using LM323K or LM350 or 7805 by helping of the power transistor. For digital load, microcontroller, even raspberry-pi.
This is 5v 12v dual power supply circuit using 2N3055 and Zener diode for 12V then to LM309 or IC-7805 dc regulator IC for 5V output which easy circuit [...]
We will use Class A headphone amplifier circuit that is very good quality sound. Consists low noise Op Amp ICs and 2 transistor as main so have very cheap [...]