in the TARDIS
from the Doctor Who TV series
which allowed the TARDIS
to adapt to its current surroundings.
Due to a short in the system, the chameleon circuit locked and the TARDIS is now in the form of a blue british police box (after a stopover on Totter's Lane in 1963 London).
The fourth doctor attempted to use the Logopolitan's Block Transfer computations to repair it, but the Master thwarted him (Logopolis). The chameleon circiut was repaired briefly again in Totter's Lane, when the Sixth doctor fought against the cybremen. The TARDIS then assumed the shape of an organ (Attack of the Cybermen)
The Master's TARDIS (Like all Tardises) is also equipped with a chameleon circiut. It has appeared, at times, as