A transporter oscillator was a component of the transporter located in the transporter room on Starfleet vessels.
In 2372, several Kazon boarded the USS Voyager after ramming their shuttle into cargo bay two, where the shields were weak. They made their way to one of Voyager's transporter rooms and stole a transporter oscillator. Maje Culluh later used the oscillator as a way for his sect, the Kazon-Nistrim to gain power in the Delta Quadrant. Commander Chakotay later took a shuttlecraft to recover it, but was captured and tortured by Culluh and Seska. (VOY: "Maneuvers")