What You'll Need

1 × Microbit v2
1 × 9 g servo motor
Micro:bit servo driver / breakout board
3D-printed bin body & lid (STL files)
Jumper wires (male–female)
USB cable & computer (for MakeCode)
Double-sided tape or hot-glue gun
Optional: paint, stickers, RGB LED strip

Safety First!

!Disconnect power while wiring the electronics.
!Supervise hot-glue and tiny screws.
!Keep fingers clear of the lid while the servo moves.
!Paint or solvent? Work in a well-ventilated space.
!Pack away cables and parts when you’re done.

Let's Make It! Step-by-Step Guide

Collect the Pieces

Step 1 of 4

Place the micro:bit, servo, driver board, 3D prints and cables within reach of everything.

The Science Behind It

A MEMS microphone converts pressure waves (sound) into an electrical signal. The Micro:bit digitizes that signal and, when it exceeds your set threshold, triggers code that sends a PWM pulse to the servo driver. Closed-loop feedback inside the servo moves the lid precisely to 0° (closed) or 90° (open). This sensor-processor-actuator chain mirrors the architecture of real-world embedded systems found in smart appliances, robotics and automotive controls, letting kids experience the core of mechatronics in a hands-on way.

Helpful Tips

Start the sound threshold around 120–140; raise it for noisy rooms.
Add small rubber washers under the servo horn for wobble-free motion.
A dab of silicone grease on the hinge makes the lid glide smoothly.
Use a 3 × AA battery pack (with 3 V regulator) for cordless operation.
Save and share your MakeCode .hex file so friends can build one too.

Try These Variations!

1IR Distance Sensor – Hands-free auto-open when someone approaches.
2RGB Fill Light – Green / yellow / red LEDs show how full the bin is.
3Bluetooth Alert – Send a “Bin Full” notification to your phone.
4Timeout Close – Auto-close the lid five seconds after opening.
5Custom Lids – 3D-print a robot face, animal snout or any design you like.

Voice-Activated Smart Trash Bin