Build Gainclone Power Amplifier LM3875 LM3876 Simply and Powerful with Schematic and PCB Layout

The chip on which the Gainclone amplifier is based, a Type LM3875 or LM3876, is a member of the Overture family from National Semiconductor, All members of this family are pin-compatible and mutually interchangeable. They are typified by an internal protection called SPIKE. In practice, the diftection ference between them is the power output. The series was described on the basis of the LM3886 in an earlier issue.

The PCB has been designed so what it can accommodate the LM3875 / LM3876 with 50 watt power amp as well as the LM3886 that 150 watts amplifier. Because of this, pin5 of the IC on the board is connected to the positive supply line. This connection is not needed for the LM3876, since its pin5 is not internally connected NC.