Cloister Bell
From Tardis Wiki, the free Doctor Who reference
The Cloister Bell was an alarm bell, located in the Cloister Room inside a TARDIS.
It went off when the Master cannibalized The Doctor's TARDIS into a Paradox Machine.
When the Cloister Bell tolled, it sounded like a big church bell. (DW: Logopolis)
In Attack of the Graske the cloister bell sounded along with a light on the Console as a warning to an approaching teleport.
