In the fine print it says they're compatible with A.C. or D.C. My friend Justin Case would stick a diode in series with the common lead.
You can start your electrical education very simply. To make direct current from alternating current, the procedure is called "rectification." You can search the web and find a plethora of explanations on how to do it, including lots of pictures of various wave forms that portray the results in easily-understood diagrams.
The basic component is a 10-cent item (or cheaper) called a diode.
One diode in series with A.C. makes "half-wave" D.C.
Four diodes wired in a so-called "bridge" creates "full-wave" D.C.
Full-wave D.C with a capacitor added creates "filtered" D.C.
That wasn't hard, was it?
To go the other way, the process of making A.C. from D.C is called "inversion." Next lesson...look up "electrical glossary." It will start to make sense.
