Step 1: Adding the OFF switch. (Also main power and RESET)
To add an on/off switch, just put a small switch between the red wire and the little board. You might as well solder on a white wire to the reset wire (white) on same board. Could also tap ground wire now too (black on board). When/if you discard the battery power, this is also where you can provide 5 volt (500 mA) power for the entire Furby.
Step 2: Volume control/Mute
This is the next easiest thing to do after an on/off switch. The speaker comes right out of the front carapace and is held to the main board with a JST 2-pin connector. Simply snip one of these wires and insert a 1-2 k potentiometer and viola- full volume control! The fur can be pulled over the potentiometer and the knob run through a small one in the fabric.
Step 3: Immobilizing and wiring Furby
Furby 2012 has a rocking mechanism on the bottom that enables back and forth as well as forward backward rocking. This could conceivably enable Furby to "wonder" off. We have chosen to immobilize the Furby by essentially hot gluing it onto an old flexible cell phone car cradle. A single screw to secure the cradle to the battery compartment, along with generous amounts of hot glue, does the trick.
Step 4: Auto Awaken The Beast
RESET button, Tail sensor, tongue sensor, tilt sensor- your choice. Any of these will awaken Furby. Any of these can be triggered using a simple relay (use logical voltage (on/off) to trigger switches on Furby. An Arduino can be set up to trigger any number (at least 8!) sensors in any pattern very easily. The solid state relay board makes this all very straight forward too as it has it's own indicator LEDS to indicate when a particular relay is closed. The eye LEDs brightness can also be very easily controlled using a single pwm pin from the Arduino.
Step 5: LED schematic
The eye LED wires are on the top/sides of the head. They are purple (+) an black (-).