Okay, technically, this circuit *does* use Op-Amps. However, the ones shown here are integrated into an ATmega128DB microcontroller from Microchip. The DIP package breaks out two operational amplifiers that are controllable entirely by software. Even better, you can program them like they are an Arduino!
James Lewis
Fan of making things beep, blink and fly. Created AddOhms. Stream on Twitch. Video Host on element14 Presents and writing for Hackster.IO. Call sign KN6FGY.