|I have an old car that has a generator instead of an alternator, so I assume it runs DC. What about newer cars? They still use a DC battery right? So what about the alternator? Doesn't that produce AC current? How does that work in a DC circuit?
Generators can produce either DC or AC power, depending on how they're arranged. A car generator was one that produced DC power. An alternator produces AC power. Since all cars operate on DC power (they use a battery, after all), the AC power is always converted to DC power. In modern cars, this is done with electronic devices, similar to those used in electronic equipment such as stereos and televisions. Converting DC to AC or vice versa is no big deal anymore. In the old days, it was harder and they used DC generators.