To determine the time of activity in school, the school bell is needed as a tool or means that gives the code of Exchange sound of that time. The digital school bell-based Arduino or microcontroller has a lesson hour scheduling capability. Utilizing Arduino Uno R3 and RTC DS3231 into an automatic school bell is a destination in the development of a button-based electric school bell whose use is still in the category of manual. Hopefully the school Bell System can automatically help the school picket teachers in carrying out their duties. The method used in research is research and development, which is analysing the needs and designing and building the system. The results of the research conducted are automatic Bell devices using Arduino Uno R3 as the driver and schedule system of the school bell as well as RTC DS3231 as the time control on the system.