Ready, Aim, Fire! Get Ready for Infrared Target Practice
WHEN I WAS A KID, I ALWAYS DREAMED ABOUT owning a laser gun—the type used in sci-fi movies to shoot those nasty aliens from faraway planets. This experiment doesn’t show you how to make a laser gun, but it does show you how you can shoot an electronic target using an invisible beam of infrared light. The experiment, shown in Figure 19-1, shows you how to make an infrared target that flashes an LED whenever it is hit by an infrared beam of light.
FIGURE 19-1 The infrared target ...