This 3V to 24 volt variable-regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3 amps or more by selecting a smaller current ...

This variable power supply is using 7805, 7809, 7812 or 7815 voltage regulators, where the last 2 digits represents the maximum output voltage of the IC. This circuit offers excellent ripple rejection ...

When reaching for a power supply design it’s normal here in 2022 to reach for a switching design. They’re lightweight, very efficient, and often available off-the-shelf at reasonable pr… ...

Indeed, you can consider the output capacitors part of a filter that reacts against the output impedance of the power-supply circuit. Increasing the value of the output capacitance will reduce noise.

The final transistor based circuit draws about 222mA — but at a 1.6% duty cycle, resulting in only a 3.5mA draw! [Paul] suspects the switching power supply inside battery pack probably draws ...