Preview to a No-Gear Rappel Anchor: How and Why to Use an Equivocation Hitch
You've run out of anchor gear, or you have damaged ropes, or you need to stay tied into the climbing rope, or... or... or; there are some compelling reasons to use an equivocation hitch for a rappel, and it can be done safely with a single rope or with doubles or with a tagline, but you better construct it correctly. The full video goes deep into setting this up and when you might want to use it.
Follow this link to the full video and accompanying blog post.