User:MentalMouse42/Sandbox/Misc Diagrams 1

Tiny Charcoal Generator
Source]

It's supposed to feed its product back into the furnace to fuel itself. However, it was an April 1 (2013) posting, so it warrants testing. At first test: Looks like it will not accumulate any charcoal in the chest until both the furnace and the hopper feeding it fuel (level 2) are full. The hopper can be "stuffed" with four non-fuel items in its last four slots, as long as you leave the first slot open for fuel. Then the chest will start getting charcoal after two stacks of charcoal are produced, which will require 2-$1/4$ stacks of wood.

If more than 5-6 stacks of wood are available, another chest can be placed atop the upper hopper.

As usual, using a hopper to take product from a furnace forfeits any experience from the smelting.