onix45:
Wow, did not think about that. Its crazy that its actually acomercial product that you can buy and on the back of it it states it outputs 12VDC 1000mA.
Well, it does, sort of. It is after all, unregulated.
There are two factors here. One is that when not loaded, the capacitor will rise to the peak voltage of the waveform. And when fully loaded at that one Amp, it will have a number of volts ripple at a frequency twice the mains, so the average will be around 12V, but deviating a few volts either side.
The second is that the windings have substantial resistance, and this is more significant in relatively lightweight transformers, so it is designed to be more than the necessary voltage, but deliver about the rated voltage when fully loaded. I am surprised the transformer read only 12V AC.
onix45:
Is this a common thing for these kind of cheapo wall adapters? Also, is there any easy way to get my 12VDC from it?
Dead normal. If you want a smooth, regulated 12VDC, you can build a regulator but frankly nowadays, you are better off to go and buy a (much more efficient, cooler) switchmode supply. Won't cost an awful lot more.