Flux capacitor

The flux capacitor was a component of the Doctor's TARDIS. (BFA: The Boy That Time Forgot)

Behind the scenes

 * The flux capacitor was the iconic core component of the time machine in the Back to the Future film series.
 * Assuming both were the same, the Doctor was apparently able to get it to activate using normal space to generate 1.21 gigawatts of electricity, and activates without needing to get the TARDIS up to 88mph.