Simple Halloween Skull

By on October 26, 2011
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Maybe it’s too late to present an Halloween project with a lot of function, so we decide to develope a simple application to show how controll a mandible of a skull.

In this project the skull speaks and moves the mandible according to the sound level.
An Arduino analyzes the level sound of a audio source and drives a servo motor connected to the mandible.
All very simple.

The video show how it works.

The sketch:



The schemtaics shows how we connect the servo to Arduino.

Download ZIP File     Download the Fritzing file


Inside the skull we use an old PCB to fix the servo (you can use what you want).

This project wants to be a start point for yours ideas….
Have a good work

About Boris Landoni

Boris Landoni is the technical manager of
Skilled in the GSM field, embraces the Open Source philosophy and its projects are available to the community.

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  • izzy dead

    how is your servo connected to the jaw? can you mount the servo the
    same as scary terry does, on his website ?

    • BorisLandoni

      We used a simple cord connected to the servo.
      You could use the Terry System of course.

  • izzy dead

    hi, i’d like to see a picture of the actual circuit too.

    • BorisLandoni

      Now there isn’t an actual circuit…. It’s an old project…

  • DS

    Can you please confirm the capacitor used…. I can not find a 1µF 6.3v electrolytic

    • BorisLandoni

      You can use also a 1µF 100V. the 6.3V is the minimum value.

  • Mike Knapp

    I followed the schematic provided in the Fritzing file and the circuit works very well. BTW – the Fritizing file contains 3 different views; one for breadboard, one for schematic, and one for PBC. All 3 views contain information about the components, namely the capacitor, the resistor, the servo motor, and the Arduino board. I used a breadboard first. The only difficulty I ran across was at first the servo only seemed to minimally respond to the audio input (I was playing a Halloween speech-based mp3) but I finally figured out that my laptop’s volume output was turned down low. Once I turned the volume up the servo reacted more robustly. I already have a skull with a hinged jaw from last Halloween and plan to incorporate this circuit into my existing design. The servo reacts very quickly to sound fluctuations and I can see it mimicking speech movement in synch with the audio track. Nice simple design! Keep in mind this circuit will also react to background music, not just speech – so you may want to mix your sound affects with the voice/speech aspects recorded on a separate track. Then you have the option of amplifying the music separately while routing the speech through this circuit.

  • Roger Kaplan

    What does the circuit do? Seems to me that it’s a parallel RC circuit, when it seems you’d want a lowpass filter which should have the resistor and capacitor in series?

    • BorisLandoni

      Arduino listen the music level and move the servo

  • Alberto Morales

    Hi guys. Sharing our techie Halloween craft for kids
    It’s an Arduino powered POV display. I hope it’ll be helpful for somebody. Cheers. Alberto Morales.

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  • Jake

    This is a silly question, but I assume you used some type of splitter for the audio cable with one end going to the arduino and the other going to amplified speakers?

  • lgn631

    Would it be alright to use your skull blueprints and code on an Instructable I am making? It’s based on how to make a full size animatronic character and your instructions would be perfect for part of the head.

  • Brian Posner

    what if i wanted to do 3 skulls… would i be able to use 1 Arduino with 3 servos with all skulls having a different movement interval

  • atomic rust

    i git thje system to work but the servo closes the mouth instead of opening it. how fix?

    • BorisLandoni

      You have to change the code

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  • Larry Liberto

    What size capacitor and what size resistor are you using?