As I've experimented and played with a lot of different sensors, I've discovered that these basic devices can be built for ...

An Arduino Uno (CH340G clone) reads temperature and humidity from a DHT11 sensor and computes 10+ environmental metrics (heat index, dew point, enthalpy, humidex, vapor pressures, etc.), outputting ...

Water level monitor using open-source microcontrollers (Arduino, ESP8266, ESP32) and ultrasonic sensors HC-SR04 / JSN-SR04T and similar with Trigger and Echo signals. Arduino Core & ESP-IDF ...