An electric current is not REQUIRED in a coffee maker, you can have a coffee maker that works on gas.
If you are going to use electricity you could design one that used DC current or AC current.
This said, as most houshold mains electricity supplies are AC, most commercially available coffee makers run on AC electricity.
depends of the type of bean used, a blend or a single origin and the roast of the bean
DC direct current
The small magnifying lens used by jewelers and watchmakers is a loupe.
Alternating electrical current is usually used in household.
some use it in coffe or to sweeten anything
DC
Alternating
AC
Alternating current
Alternating current.
You will have to specify if you mean current maker, past maker, one with history (i.e. scope used on rifle to assasinate a prominent figure, etc..)
Energy