Fingerlings Fart Monkey Autopsy

Fingerlings are Cabbage Patch Kids multiplied by Bitcoin. Let’s sacrifice one for science and see the tech that makes them so irresistible!

Read on to the end for a shocking video showing how we may reanimate a disemboweled fart money when animal electricity is duly applied…

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Even though these fart monkeys have sold for up to $249 on ebay, they retail for for only $15. Let’s see the tricks WowWee used to make an interactive and emotional robot with that budget!


  • Sound via microphone in head
  • Orientation via tilt sensors on board
  • Touch via capacitive sensors in head


  • Sound via speaker behind mouth
  • Eye blinks via magnetically actuated eyeball assembly
  • Headturns via gear motor

My Eyes

A tiny coil pushes on a magnet to make the eyes blink.


I love this mechanism because it is simple and there is almost nothing to break. The only moving part is the plastic eye assembly and it is held in place by molded open hinges on either side. You can not damage anything by manually moving or restraining the eyes.

The eyes also have a nice little built in counterweight to reduce the force needed to blink and also make them automatically close when laying down.


And thusly we may cause an electrical current to flow from a voltaic pile and cause reanimation of the eyes…

Touch Pads

Inside the head there are two strips of foil tape that act as captive sensors. This is a very cheap and robust solution to detect when each side of the head it being pet.

These work by sensing the change in the capacitance when something like a giant bag of salt water (your finger) is close.


The Neck

The neck has a pretty normal gear motor with a cam that activates a limit switch on the printed circuit board. This switch lets the firmware know when the head has reached the end of its travel so it can stop turning the motor.


This is a disappointing solution to the problem.  That switch is expensive and has lots that can go wrong. It also puts strain on the motor and gear train if you manually hold the head while the motor is trying to turn it.

Maybe a better solution would have been to use the motor current to detect when it was stalled from hitting one of the endstops. This would cost (at most) single resistor and has the added benefit that motor would automatically stop if you put too much load on it (like holding the head while it was trying to turn).

Otolith Organs

The monkey can tell which way is up using two orthogonality mounted tilt sensors on the circuit board.


We’ve seen ball filled sensors like these before. They are cheap and work well.

That double triangle plastic piece under the sensors seems unnecessary- those are not going anywhere. Maybe these two sensors come as a single assembly already mounted to the plastic?

The Mohawk


I wonder why they needed that extra wedge piece to hold the mohawk? Seems like it would have been completely constrained even without it. Any ideas?


Mostly standard injection molded parts, but the arms and legs do have a nice rubber(-ish?) overmolding to make them softer and tackier. I’ve heard that knock-off fart monkeys do not have this.



The hands and feet are dipped in white paint.


Perfunctory video

Its object is to show the excitability of the frame, when animal electricity is duly applied. It promises to be of the utmost use, by reviving the action and thereby rekindling the  spark of vitality.



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