i have a motor that need dc current but i don't have the equipment with dc i have only ac. what is the difference of ac and dc
AC voltage alternates polarity 60 (50 in Europe) times a second, meaning the AC current changes direction that often. Only AC is good for transformers, and AC motors tend to be more efficient and constant speed. You just need to know what DC voltage you need for the motor. If it's 12 volts, most people will just use a car battery for a source. You can hook batteries in series for higher voltage. You can also buy power supplies that turn AC into different DC voltages.