Is there an app that could send me a notification every 30 minutes?

They say time is is the most valuable resources. Right now, time feels quicker for me these days and I often lose track of it.

Because of that the app should have the same purposes as an old clock, it plays a little "ding" or a notification every 15 minutes, 30 minutes, or 1 hour, or as long as I like.

Preferably installable with f-droid, can I have an app recommendation.