Noise due to incorrectly dimensioned power supply

First I have to say, the operation and functions of the alarm clock I loved. It is easy to use, and does exactly what it should. In principle, I would be thrilled, and would not give him back - but ....

The power supply of the alarm is a steady high-frequency "hum" of itself. The volume will increase, consume the more power the alarm - for example by switching on the projection and charging a mobile phone.
Once the projection is on, the alarm makes noise loud enough to disrupt sleep later strongly.
This is for an alarm clock, the classical manner next to is therefore a "no-go" only 1 star.