““ADD A BUZZER TO YOUR GAME Congratulations: You’ve finished the last project in the book! Now, it’s up to you to decide what to make next. If you’re not sure where to start, why not add more circuits to your reaction game? The LED in the middle is where you want the light to stop, and I suggest adding a sound circuit to bring some excitement to hitting your target. To do this, you could use an active buzzer like the one in “Project #2: Intruder Alarm” on page 11, as shown in this partial circuit diagram. The darker part of this circuit shows new components you’d need in order to add a buzzer to the reaction game project. The lighter components are just a section of the original circuit diagram. Connect the positive leg of the middle LED through a 1 kΩ resistor to the base of an NPN transistor. Then connect the buzzer to the transistor’s collector. Connect the positive side of your battery to the other side of the buzzer, and connect the negative side of the battery to the transistor’s emitter. You should end up with a circuit that makes a little beep every time the light passes the middle LED. If you can stop the light on the middle LED, the buzzer should beep continuously to indicate that you’ve hit the main target. When you’ve customized the game to your liking, solder it onto a prototyping board. Maybe you’ll even want to place it in a nice box to hide the electronics and show only the buttons and LEDs.””
