Build a smart dustbin

Turn an ordinary bin with a hinged lid into a touch-free one: an ultrasonic sensor sees your hand, a servo lifts the lid, holds it open, then closes it gently.

Time1–2 weekends

Parts₹984–1,265

The sensor sees a hand4 wires, 5 actions · read it below
The servo on its own power10 wires, 6 actions
Lid linkage, torque-checked7 actions
Opens for a hand6 actions
No flapping, gentle closing6 actions
Finished and in use1 wires, 6 actions

Start this build

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Before you start

Tools: Laptop with the Arduino IDE, Multimeter, Kitchen scale and a ruler, Screwdriver, and a hand drill with a 3 mm bit, A bin with a lid hinged at the back (flip-top or pedal bin)
Skills: A first servo project with a little hand-made metalwork or woodwork. No soldering. Steps 1, 2, 4 and 5 use code (or Get the code); step 3 is mechanical.
Safety: Low voltage at the bin: 5 V for the servo, from a 12 V plug-in adapter. Use a closed, shop-bought adapter and never open it. A closing lid can pinch fingers: the code closes it slowly and reopens if something is in front of the sensor, but it can't see fingers at the rim or hinge: keep them clear. Keep the electronics away from wet rubbish.
Prices: Checked 2026-10, with a clone Uno and an SG90 for a light lid; the top figure has an MG996R for a heavier lid plus the optional LED and buzzer. Not counted: the bin itself, scrap for the bracket, M3 screws, foam tape, cable ties and the electronics box. An original Uno adds about ₹1,950

Step 1 of 6

The sensor sees a hand

The ultrasonic sensor measures distance, and you've found a spot on the bin where it sees a hand but not the floor or the wall.

Build it

Task 01 of 05

Unplug USB, then wire the sensor to the Uno one wire at a time.

Check: VCC goes to 5V and GND to GND. Swapped, the sensor can be damaged.

Safety: Unplug USB before you change any wire.

Steps
Wires · 4
Steps

You need

Arduino Uno R3 and USB cable
HC-SR04 ultrasonic sensor
400-point breadboard
Jumper wires (male-to-male and male-to-female)

HC-SR04 GND
HC-SR04 VCC
HC-SR04 TRIG
HC-SR04 ECHO

Uno GND
Uno 5V
Uno pin 9
Uno pin 10

Serial monitor

9600 baud

Expect to see

Distance in cm, about 10 times a second: not seen yet63.7 cm
NEAR is added when your hand is closer than 25 cm: not seen yet18.2 cm NEAR

Get the codeThe full sketch comes with the build.

Build a smart dustbin

Parts list

The sensor sees a hand

Build it

Serial monitor