TL;DR
David Johnson-Davies has created a versatile DIY Digital Signal Generator that can replace a whole collection of oscillators. This device can generate frequencies ranging from 2 Hz to 33.5 MHz in precise 2 Hz increments, making it a handy tool for anyone working with microcontrollers, FPGAs, or even vintage CPUs. Instead of relying on traditional timer circuits, Johnson-Davies utilizes the Numerically Controlled Oscillator (NCO) feature of Microchip Technology's AVR EB-series microcontrollers, which allows for accurate frequency generation across a broad range.