The Ovilus, or Puck, is an electronic speech-synthesis device which utters words depending on electromagnetic waves in the air, by using an EMF Meter. The device was created by Bill Chappell, a retired electronics engineer interested in the paranormal who creates devices for the field.
The Ovilus has an embedded database of words. It contains an EMF Meter. These readings are combined to create a number, and this number is used to reference the database of words. The Ovilus then "speaks" that word. An Ovilus can also operate in a phonetic mode that reacts to EMF variations to create words that are not in the database. There are other types of the Ovilus device, including the Paranormal Puck, Video Ovilus, Ovilus I, Ovilus II, Ovilus FX, Ovilus X (pictured above right), Talker, and The PX. It's a bitch bro!!!
Ovilus is marketed as an entertainment device. It is used by many paranormal groups and has been used on Paranormal State (Season 2 Episode 6, "Hells Gate"). During this episode, the device is explained and given a few minutes of air time. A variation of the Ovilus, Video Ovilus, one with a built-in night-vision video camera, can be seen on Ghost Adventures in several episodes. Paranormal aficionados claim the device is a conduit to allow communication with spirits.
The manufacturer does not claim that the device allows communication with the dead. Reviews have been mixed.
Due to the random nature of the replies, many paranormal research groups have stopped using the Ovilus because too much is left to chance. It is posited that a person could pull random words out of a hat and get the same response as what comes out of the Ovilus. Many liken it to an electronic 8 Ball or Ouija Board.
Despite the label that says, "For Entertainment Purpose Only", the device is still used today in paranormal research. Groups claim that it has replied with very accurate words relating directly to the case they were investigating.
From the maker's website, the odds of actually getting a response that is related to the question a person asked are one of the following: 1:512 (Ovilus I), 1:1024 (Ovilus FX/Video Ovilus), 1:2048 (PX), or 1:2048+,- (Ovilus II/Ovilus X, due to their user-changeable dictionaries). There are anywhere from 512 words to over 2048 in the database, depending on the type of Ovilus that is used, so basically you have an even shot to get a response that fits in a contextually accurate fashion.
There is also a mode called "Phonetic mode". Within this mode, words can be put together that are not in the list of words listed above. According to the owner, complete sentences are possible, but not a feature of the device. In Phonetic mode, the odds of a related response are 1:71, the phonetic generator carries those same 1:71 odds no matter what model of Ovilus is used.
As an EMF meter
The devices contain several LED lights that correspond to the level of EMF in the room. The manufacturer states that this meter is not an average sampling but a real time sample. This meter should not replace a device that is a dedicated EMF Meter. Though there is no evidence that EMF meters have any efficacy in detecting ghosts or other supernatural entities, paranormal researchers are still using the EMF meter based on the event that the meter has picked up readings on request or in locations where there was no explaination for the meter to spike.