In this lesson, we have seven projects in one. We learn how to use the DS1307 Real-Time Clock (RTC) module to build a clock using Arduino.

This is project 2-3. In this project, we learn how to use the DS1307 as an alarm clock, where we set a specific date and time for our alarm, and one output pin of the Arduino is turned on using the alarm. As shown in the video, we first turn on a buzzer as an alarm, and then the wiring diagram is shown for connecting an AC bulb or any other device to the relay. A relay is just a mechanical switch to turn something on or off.