In this simple circuit, we use a small BH1750FVI sensor on a breakout board and an Arduino to measure the illuminance in lux. Besides the application to measure the illumination of objects in the photography, you can – with an extension of this circuit – also easily make an adapted illumination of rooms or gardens. It is also possible to realize an automatic brightness control for displays.
On the way to a small weather station we deal today with the air pressure and temperature measurement and use a breakout board for the BMP085 with an I²C interface, and an Arduino of our choice.
The DHT11 is a simple and inexpensive temperature and humidity sensor, which is ideal for small projects with the Arduino, in which it does not depend on a high degree of accuracy of the measurements. It should be used for indoor measurements.
Sensors, like the DHT11, are virtually the senses in the world of microcontrollers. With them you can observe, for example, environmental influences, and possibly respond. In this case we deal with the temperature and humidity measurement and therefore we have almost a small weather station.
The GY-65 is a simple breakout board for Bosch BMP085 barometric pressure sensor with integrated temperature measurement. The values can be a simple used for weather forecast, more precise (GPS) navigation (level measurement, as well as vertical climb and descent).
The HC-SR04 is a very inexpensive ultrasonic range sensor. He is primarily in robotics and autonomous vehicles in use, being possible to use the sensor for example for obstacle detection, but also level indicators or motion detection are possible with this sensor.