A tape recorder was a device used to record and play back sound.
The First Doctor used a tape recorder to record and play back a tune which the Pied Piper played on his pipe. (COMIC: Challenge of the Piper)
In the 1970s, General Carrington had a tape recorder which automatically played back Charles Van Lyden's voice placed inside Mars Probe 7 to delay Space Control in opening it. (TV: The Ambassadors of Death)
A few years later, when London was evacuated, Lodge stayed behind to loot; he stole, among other things, two tape recorders. (TV: Invasion of the Dinosaurs)
Gordon Hamilton's father used a tape recorder in the Solar Queen to play back a radio message warning Earth about the Zarbi Supremo. (PROSE: The Lair of Zarbi Supremo)
In 2493, Bennett used a tape recorder which automatically played back his voice to fool Vicki into thinking he was still in his cabin on the UK-201 while he was disguised as Koquillion. (TV: The Rescue)
On Kembel in 4000, Marc Cory used a tape recorder to record a message warning of the Dalek plot to invade and destroy the galaxy. (TV: Mission to the Unknown, The Daleks' Master Plan)
On Skaro, Davros used a tape recorder to record the Fourth Doctor's knowledge of the Daleks' future defeats. (TV: Genesis of the Daleks)