A smartphone holder - turn an old smartphone to an alarm clock (at a wall socket)

I like to use my old smartphone as a very convenient alarm clock. But because I do not want to sleep with a smartphone nearby, I have managed it in a different way. My model allows to put an old smartphone with it's charger in a socket at any place. Just it is important to hear the music from that. My idea is to use a short soft music (20 seconds) and just the long silence after. So this alarm clock wakes me up softly (it is possible to set a different time for different week days), and it does not need to be silenced manually. It also stays a few meters away from my bed. That is what I need.

This is a version is ideal for Samsung J7, but I have added an iPhone 11 as an example, too (with it's official dimensions). 

There are many alarm clock apps on Google Store or App Store.