Control a small DC fan from a temperature threshold with a transistor or MOSFET, flyback protection, and hysteresis; this is not an AC-unit controller.
Use an IR remote to toggle eight relay channels in a low-voltage demonstration, leaving mains design and installation to qualified professionals.
Identify whether a breakout contains HMC5883L or the common QMC5883L alternative, then calibrate hard-iron and soft-iron distortion before computing heading.
Receive bounded text from an Android Bluetooth terminal, sanitize line endings, and wrap it across a 16×2 LCD.