Book excerpt: This second volume of the ­Arduino Project Handbook delivers 25 more ­beginner-friendly electronics projects. Get up and running with a crash course on the Arduino, and then pick any project that sparks your interest and start making! Each project includes cost and time estimates, simple instructions, colorful photos and circuit diagrams, a troubleshooting section, and the complete code to bring your build to life. With just the Arduino board and a handful of components, you’ll make gadgets like a rainbow light display, noise-level meter, digital piano, GPS speedo­meter, and fingerprint scanner. This collection of projects is a fast and fun way to get started with microcontrollers that’s perfect for beginners, hobbyists, parents, and educators. 25 Step-by-Step Projects LED Light Bar Light-Activated Night-Light Seven-Segment LED Countdown Timer LED Scrolling Marquee Mood Light Rainbow Strip Light NeoPixel Compass Arduino Piano Audio LED Visualizer Old-School Analog Dial Stepper Motor Temperature-Controlled Fan Ultrasonic Range Finder Digital Thermometer Bomb Decoder Game Serial LCD Screen Ultrasonic People Counter Nokia 5110 LCD Screen Pong Game OLED Breathalyzer Ultrasonic Soaker Fingerprint Scanner Ultrasonic Robot Internet-Controlled LED Voice-Controlled LED GPS Speedometer Uses the Arduino Uno board