German torpedo fuses, how do they work?

From a channel Lumen includes in full: Drachinifel covers naval history ship by ship and battle by battle, with design, doctrine and operational detail drawn from naval records and specialist literature; long-running and respected among naval historians.

A 16-minute video from Drachinifel's catalogue; the title names its topic.

Video by Drachinifel, played through YouTube's embedded player.