Relay on alarm

Hello, i have a project in which i want to use a relay with an arduino uno to sound the alarm automatically when the classes are finished. For example if it's 7:50 then it should ring 3 times for 2 seconds with a 2 second break between, and at 8:00 to ring it again the same way. I need some help because i don't really know how to get the date and time into the arduino so it could know exactly when to ring the alarm, i want to make it ring from monday to friday at these hours: 7:50, 8:00, 8:50, 9:00, 9:50, 10:00, 10:50, 11:10, 12:00, 12:10, 13:00, 13:10, 14:00, 14:10, 15:00.

The most basic way is adding a RTC module to your Uno.

https://playground.arduino.cc/Main/DS1302

When your coding skills improve you can use a WiFi enabled Arduino, like the WeMos D1 mini, with relay shield.
Then you can get time off the internet, including daylight savings, so you don't have to constantly adjust the clock.
Leo..

Wawa:
The most basic way is adding a RTC module to your Uno.

Arduino Playground - DS1302

When your coding skills improve you can use a WiFi enabled Arduino, like the WeMos D1 mini, with relay shield.
Then you can get time off the internet, including daylight savings, so you don't have to constantly adjust the clock.
Leo..

Do RTC modules have a lot of drift in time where the clock must be constantly adjusted? I guess so, I saw some talk of this on an old thread in case the OP wants to look into further. Thanks for teaching me something new Wawa!

The first part of the article I linked to explains why you should use a DS3231 module.

And yes, we have to adjust our clocks twice a year here (daylight savings).
Leo..

Thank you for your help !