Earthmen Detector
From Tardis Wiki, the free Doctor Who reference
The Earthmen Detector was an object which the Daleks created to help detect hiding humans. It was equipped onto the Dalek casing through a band encircling the base unit.
When the Daleks tested the prototype, the device went off at the exact moment that a cat passed it, making them think that it was defective. The Daleks left to destroy the useless artefact, as the First Doctor, Ian and Barbara came out of hiding. (COMIC: The Daleks Are Foiled)
