Roy divided these machines into two groups. One group he labeled true perpetual motion machines, because they require no outside energy source. These mechanisms, typically an assortment of wheels and weights, would violate the laws of thermodynamics if they actually worked as claimed. The other group of perpetual motion machines appear to work because they tap an unknown or unrecognized energy source. Another typical quack invention, also appearing in countless forms, is the black box.
Black boxes are typically secret electrical mechanisms claimed to perform remarkable tasks.
An example is the E-Meter used by the Church of Scientology in personal counseling. The E-meter is claimed to be a scientific method of determining the causes of psychological problems. In fact it is an assortment of inexpensive electrical parts that does nothing. Another black box quack invention, also proposed as a tool to use in psychological counseling, is Wilhelm Reich's Orgone Energy Collection Box. Reich's Box is as phony as the E-Meter.