Alimentation linéaire CA-CC 9V CC @ 1000mA; 2,1 x 5,5mm polarité centrale (+)

So sorry the power supply was not a match for your needs. A linear AC-DC power supply (non-regulated) will always read about 1.5x higher on a no-load read. The 9VDC will probably read about 13-13.5VDC. A regulated or a switching type power supply (are always regulated) will give a constant steady volt reading with a +/- of 0.2V within its stated voltage.

Whereas an AC-AC linear power supply will read about 1VDC higher on an open/no-load read.

So sorry the power supply was not a match for your needs. A linear AC-DC power supply (non-regulated) will always read about 1.5x higher on a no-load read. The 9VDC will probably read about 13-13.5VDC. A regulated or a switching type power supply (are always regulated) will give a constant steady volt reading with a +/- of 0.2V within its stated voltage.

Whereas an AC-AC linear power supply will read about 1VDC higher on an open/no-load read.