More fun to do is to use LEDs flashing all sensors to detect what is happening "out there" and react accordingly. Unfortunately, each sensor has its own methods of connection: some need resistance "pull-up" and some not, some need their own sources of power and some not, some work to much stress and not others, etc. In this chapter the most common sensors are presented with examples of circuits that are used and Arduino code that make them work. He also indicated for each specific type of sensor which specific products can be found in different distributors. However, if desired, can be...