““MEET THE REACTION GAME CIRCUITS The reaction game will consist of three circuits: A 555 timer circuit that determines the speed of the game A counter that controls which LED light to turn on An SR latch that will add a reset button and an action button This section explains each circuit, but to help you understand their diagrams, let’s meet two new circuit symbols. Meet the VCC and GND Symbols Circuit diagrams don’t always use a battery symbol like the one used throughout this book. Sometimes they use the VCC (or VDD) and GND symbols instead. If nothing in the circuit diagram or its description says otherwise, you can assume that VCC represents the positive side of the battery and that GND represents the negative side, or ground. The symbols sometimes look a little different, but the VCC symbol usually shows a wire connecting down from its symbol to the circuit, while the GND symbol shows a wire connecting up from the symbol to the circuit. In bigger circuit diagrams, like the one you’re going to build from in this chapter, these symbols make the diagram much easier to draw and understand.””
