This project demonstrates a design of a simple circuit and a box that can be unlocked using a specific knock. The circuit consists of an Arduino uno, a microphone, two LEDs, and a servo motor. The box can be made with your own design and creativity, but if you have access to a laser cutting machine, you can use the design uploaded in this instructable to make your box using acrylic. The video shows how the box responds to the secret knock.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.