Why the furby?
The furby is the perfect platform to deconstruct electromechanical systems, compare them to their biological counterparts, and delve a bit into the psychology of why we like cute things.
The furby was designed as a tomagatchi you could pet, i.e., the tactile nature of the furby is just as important as the moving gears and software personality. It has big eyes and ears relative to the body, large head, a rounded shape, soft fur, and small mouth with a tongue. The furby is also safe. Nothing on a furby can harm you. These are all features seen in babies and young juveniles in both domestic and wild populations. They signal that the animal is helpless and needs protection. In fact, the more furbies you buy, the more you can protect, right? The furby is economics + robotics + social change + evolutionary theory.
Sensors on the furby: light sensor, IR sensor, three touch sensors, sound sensor, and a tilt/upside down sensor.
Motors on the furby: only one! Driven by a gearing system.
"Brains" in the furby: Two! A main microprocessor and a separate "speech center".
Sum of Our Parts
It's been a little while, so let's refresh your memory before we continue with the dissection.
Whew, glad that done. OK, part 2 is all about taking apart the different components and thinking about the different sensory systems of Furbis generalis. Your going to have accept the fact that this furby may not ever be fully assembled again. It may have to be pulled, pried, or cut apart. Plastic will fail and tiny screws will fall off your table to disappear forever into your carpet. But what we loose in taking apart an addictive ball of cuteness, we gain in our understanding of mechanical form and function.
For instance, here is a diagram I recently made for an art show:
2. Orient yourself. The main body (1) houses the motor, gears, and electronic components. The base (2) houses the four AA batteries, the red and white speaker housing, and a button (more on all that later). The base in adults is partially inclined and the speaker is red and black, not red and white.
3. To separate the main body from the base, you have to unclip one set of wires, and cut another*. First, follow the wires from the speaker to the circuit board.
*FOR THE ADULT: you will have to clip all wires due to some aggressive gluing by the manufacturer.
It may take some force to get the clips to release. I found my surgical towel clamp tool to be very helpful.
4. Cut the four remaining wires going from the base. Two will be red and black. These are the power cables. The other two will be grey (like in the picture above) or black. If you look closely, these two are running from the reset button on the base of the furby to the circuit board. This will run the command to reset the program (aka software, aka furby thoughts) if necessary.
There also might be a lot of messiness and glue from the manufacturing process.
5. After celebrating your victory, unscrew the white and red panels from the front of the base. You will find two metal plates under the first (white) layer. This is part of the furby's sensory system. When the two metal plates are connected, it sends a signal to the computer chip (brain) that the furby's stomach has been patted/poked.
Within the red plate is the speaker. Although Furby has a mouth, you can now see that the mouth is really only for sensing. The energy comes from the batteries and the voice through the belly speaker. Strange for an animal, perhaps, but not a robot!
The picture above shows the speaker (orange wires) with the tummy button (grey wires) still attached. Notice that, for ease of manufacture, these wires all lead to one clip. This is true for the adult as well, there is just a little more glue involved.
6. Now comes the fun part: removing the head from the circuit board. First, remove the four remaining clips...
7. Now that you've undone all the clips, you can flip open the head from the circuit board.
8. Now cut the two remaining wires (red arrow in above picture) so that the circuit board and the head are separated. We will look more at the head in Part 3. The rest of this tutorial will look at breaking down the circuit board and appreciating the PCB* revoltuion.
*printed circuit board
9. The parts:
The microphone was embedded in right hemisphere of the plastic shell. It's debatable how sensitive the microphone is. It likely just responds to noise above a certain volume or frequency. Note that all sensory on the furby appear to be wired with yellow and green wires in the juvenile.
Capacitors store electricity and discharge it when the flow goes below a certain level. Useful for maintaining a constant electrical flow.
Diodes are used to make sure a current only flows one way.
Resistors are used to control (and usually limit) the level of electron flow.
Inversion Switch- the switch on the juvenile is red, but in the adult I have the cylinder is clear and you can see a round metal ball sitting on two almost touching metal plates. If you shake the furby you should be able to hear the ball. When the furby is turned upsidown the metal ball hits two other almost touching metal plate on the top of the cylinder, breaking the connection on the bottom and forming one at the top. This would send a signal back to the furby's microprocessor.
Logic Gate Chip- I'm being a little vague here, but these are likely being used to direct electricity at different functions depending on the behavior of the furby. For instance, if the furby gets turned upsidown and, hence, gets input from the top plates of the inversion switch (see above), the closed electrical circuit may switch a gate in the chip and send electricity from 'sleep mode' to 'awake mode'.
Microprocessor under epoxy blob- much has been said about the "brains" of the furby. I will link more in-depth discussions in the references below. For now, know that the microprocessor is thought to be where the furby gets its personality and where behavior is controlled. The exact make, model, and code of the microchip is a mystery thanks to the plastic blob covering everything.
Secondary Microprocessor under epoxy blob- the secondary chip is thought to be a word database for the furby. This would make the furby easy to manufacture in different countries, as this "language center/ Broca's area" could just be switched and everything else on the furby would remain the same.
10. Now flip the circuit board around. You are now looking at the "bottom" of the circuit board, the part that would contact the base.
10(cont.). For this picture, the top is flipped back on (like Step 6). This is to show how the hole in the circuit board (light blue arrow) is used to pass through a part connected to the gearing system. This part pushes on the furby base, causing the head to wobble and nod. You will see this part again in Blog 3. You can also see a blue and a white wire. These relay power from the batteries.
Removing Furby's brains!!!
Reference (PLEASE CHECK OUT THIS AWESOME WEBSITE)