Single Output Supply
This is a simple power supply circuit providing general purpose voltage regulation using the popular LM78xx linear regulators. A power supply module like this is useful for a lot of projects and is easy for beginners to build and understand. The regulators are inexpensive and can also be scavenged if you have a stash of circuit boards from broken electronics. I typically use this to regulate the voltage from a wall wort to power various circuits/projects.
There's not much to understand in this design, it's just a few capacitors to filter the DC input and output from the regulator. A diode prevents damage from reversing the power input connections. If you don't want the diode you can replace it with a jumper wire. This design includes a power switch and power LED to indicate when the circuit is turned on. Several output connections were added to allow the supply to run multiple circuits in a more complex project. Use a small heat sink on the regulator to prevent overheating if you're powering a heavy load.