20 Amp variable power supply with an output voltage from 1.5 to 15 volts using the LM317 regulator and 4 2N3055 power transistors to amplify the current capacity

This 12V to 9V DC converter is very useful for powering 9V DC devices in a car that uses 12V battery. The maximum current consumption allowed by this circuit is 0.8 amps.

This 1.5 V Joule Thief circuit can turn ON one LED. The circuit doesn’t use a toroid coil, but you can turn on a common red, green, or yellow light-emitting diode (LED).

This variable power supply uses the LM350 adjustable voltage regulator and can deliver 1.25 to 16 volts and a maximum current of 3 amps.

This Power source can be used to power circuits or electronic devices that would normally use a 9 volt battery, saving us the cost of the battery while being used at home.

4 Amp Variable Power Supply with 3 LM317 voltage regulators and a LM308 precision operational amplifier. Output voltage from 1.25 to 30 volts.

Variable power supply with LM317 and boost transistor (4 amps) circuit. How it works. The high/low voltage selector switch. List of components

This 12V 1A power supply using zener diode and transistors allows us to obtain an output of approximately 11.4 volts with a very small percentage variation for a wide variety of loads.

15V power source ON delay using LM317. This circuit uses the LM317 voltage regulator. It also uses a transistor and an a electrolytic capacitor

This 12 VDC to -12 VDC converter circuit gives -12VDC (negative 12 volts) from a power source of + 12VDC (positive 12 volts), with very few components.