Perpetual electrical generators are possible or are a fraud?

Many ads and videos are in the internet where plans for the construction of perpetual motion power generators are sold, anybody here know firsthand if these artifacts really work or are just a fraud.?...

mmm, looks like a fraud to me but it could worth to see one actually working, then we could decide, hope somebody had already tried one and post in this forum, but it will take sometime because this forum in new.