This topic might have a better name.
Machine that goes ding or Zygon detector.
Talk about it here.
A Machine That Goes "Ding" was a machine that the Tenth Doctor used to detect Zygon DNA.
Besides lighting up when in the presence of a Zygon, the machine could microwave frozen dinners from up to 20 feet and download comics from the future.
The Doctor thought the machine identified Elizabeth I as a Zygon, but it had in fact detected that her horse was one. (TV: The Day of the Doctor)
Behind the scenes Edit
It resembled the Timey-wimey detector from Blink in many ways, being made of a bunch of random objects, making a "ding" sound, and being able to remotely prepare food.