Environmental Monitoring with Arduino

Electronic Circuits and Components

An electronic circuit is, as the term implies, electricity moving in a path very much like a circle. Each circuit has a beginning, a middle, and an end (which is usually very close to where it began). Somewhere in the middle, the circuit often runs through various electronic components that modify the electrical current in some way.

Each device in this book is a circuit that combines Arduino with different electronic components. Some of these essentially manage the power and path of the electricity; others sense certain conditions in the environment; and still others display output about those conditions.

Let’s take a look at some of the components we will be using in our circuits:

Light emitting diodes (LEDs)

An LED is a lamp made of various rare-earth metals, which give off a large amount of light when a tiny current is run through them. The composition of the substances within the LED determine the particular wavelength of light emitted: green, blue, yellow, red, and even ultraviolet and infrared are among the possible colors.

Technically, the LEDs used in our gadgets are “miniature LEDs,” tiny lamps with two wire leads, one long (called the anode) and the other a bit shorter (called the cathode). These come in various useful forms, including single lamps from 2mm to 8mm in diameter, display bars, and alphanumeric readouts, and can serve as indicators, illuminators, or even data transmitters.

You’ll learn how to use these different types of LEDs ...