This project uses the on-board microphone of the Circuit Playground Express's to trigger a pair of servo actuated costume ears to perk up when there is a loud noise. The ears are mounted on a hair band and the whole thing is completely self-contained. 


This project uses a Circuit Playground Express, 2 servos, and a LiPo battery. Any size battery can be used, but the 1200 mAh model is a good balance between size and lifespan.

A Black woman's manicured hand holds a round microcontroller with lit up LEDs.
Circuit Playground Express is the next step towards a perfect introduction to electronics and programming. We've taken the original Circuit Playground Classic and...
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Micro servo with three pin cable
Tiny little servo can rotate approximately 180 degrees (90 in each direction) and works just like the standard kinds you're used to but smaller. You can use any servo...
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Lithium Ion Polymer Battery 3.7v 1200mAh with JST 2-PH connector
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
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Group of Small Alligator Clip to Male Jumper Wires
When working with unusual non-header-friendly surfaces, these handy cables will be your best friends! No longer will you have long, cumbersome strands of alligator clips. These...
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  • Headband
  • Construction paper
  • Corrugated cardboard
  • Hot glue and glue gun
  • 2 rubber bands of an appropriate size
  • Felt, faux fur, or fabric as desired to cover the ears
  • Jumper wire with male pins if you want to solder to the CPX for a more robust connection
  • flexible/stranded wire to use as an actuator
  • 4 pieces of stiff wire (long male header pins work well) and wire to mechanically connect the servo 

This guide was first published on Aug 22, 2018. It was last updated on Apr 22, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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