DDS sine signal generator for AM modulation from 1 Hz to 40 MHz with an AD9850 or AD9851, an ATmega328, and an Arduino firmware | Electronics and Mechanics for Hobbyists
InvIoT.com - Wave Generator - Signal Generator (arduino compatible)
Arduino Tone Generator – Simple DIY Electronic Music Projects
Function Generator (Sine, Triangular, Chainsaw, 32 kHz Max) - Hackster.io