Zigzag plotter
From Tardis Wiki, the free Doctor Who reference
The Doctor's TARDIS once had a component called the zigzag plotter which looked like a car gear lever. The zigzag plotter only worked if the operator stood in a specific place while using it. The Eleventh Doctor talked Amy Pond through its use to stop the TARDIS from being thrown into the Time Vortex with only her inside. (DW: The Lodger)
