L7812 12 V Fan Supply

A classic three-terminal linear regulator turns a noisy 18 V wall-wart into a clean 12 V supply for cooling fans and small motors.

Difficulty: Breadboard. Estimated build time: about 25 minutes. Estimated parts cost: about US$2.90. 4-part bill of materials with live supplier pricing. A clean 12 V power supply built around the L7812CV, the 12 V member of the legendary 78xx family of three-terminal linear regulators.