Need Some Electrical Expertice

[nachoman]

Bear in mind that this power supply is most likely unregulated. That is, the output voltage can vary, dependent on the load. The higher the load (more current drain), the lower the voltage will be. If you need a more precise voltage output, then it's best to look for a regulated supply rather than this one.

I wonder about that. I tore into a small wall wart a few weeks ago and was surprised to learn it was regulated. It should probably say in the description on the packaging, right?