The DS-1307 is often the default choice for an RTC. However, if you need advanced features like alarms or square wave outputs, it’s best to look upmarket. The DS1307 has the proud title of being ...

This replica uses LEDs driven by an Arduino Nano and a real-time clock. Since the RTC gives hours from 0-23 and minutes and seconds from 0-59, a couple of shift registers and some modulo ...