A LM7812 Voltage Regulator is a voltage regulator that outputs +12 volts. The LM7812, like most other regulators, is a three-pin IC. Pin 1 (Input Pin): The Input pin is the pin that accepts the incoming DC voltage, which the voltage regulator will eventually regulate down to 12 volts. Pin 2 (Ground): Ground pin establishes the ground for the regulator. Pin 3 (Output Pin): The Output pin is the regulated 12 volts DC.