Dr. Venkman used “one of our little toys” before the proton packs were ready, the Ghost Nabber™ (drawn in 1986 as Ghost Detector) was created for The Real Ghostbusters. The Ghost Detector was seen and used three times during The Real Ghostbusters. It was first seen as a “movie prop” in the first season episode Take Two. It made an appearance in the season 3 episode Loathe Thy Neighbor.
Ray used the Ghost Detector to confirm Egon’s reading of the Ogre ghost in the season 3 episode Big Trouble With Little Slimer.