Lesson 9 Introducing Transistors

Chapter Lesson 9 Introducing Transistors

Electronic Circuits for the Evil Genius Second Edition 64 Lessons with Projects
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Electronic Circuits for the Evil Genius Second Edition 64 Lessons with Projects

  • a.As you replace each capacitor and recordthe time, the LED stays on. Don’t expectthe time to be very exact.b.Describe the pattern that you see here.__________________________________5.Briefly describe what capacitors do._____________________________________6.Place the 1,000-microfarad capacitor backinto its original position. Now replace thenormally open push button (PBNO) with thenormally closed push button (PBNC).Describe the action of this circuit.Lesson 9Introducing TransistorsLearning electronics is not hard. Itis lots of new information, but it isnot hard. Think about it, but not as hard as the guyin Figure L9-1.Considering that it has only been a bit more than100 years since the first transatlantic radio message,electronics is a young technology. The invention ofthe transistor in 1947 was the first step towards themicrosizing of all electronics we use today. TheNPN (negative-positive-negative) is truly electronic.It acts like a normally open push button, but has nomoving parts. The transistor is the basic electronicswitch. It does have an interesting history thatmakes for good outside reading. Our entireelectronic age is dependent on this device.Transistors are commonly packaged in the TO-92case shown in Figure L9-2. Notice how the legscorrespond to the schematic symbol in Figure L9-3.Note the arrow inside the schematic symbol. Itindicates two things: First, it points in the directionof the current, towards ground. Second, it is alwayson the side of the emitter. It is important to identifythe legs of the transistor. For this package, it iseasy to remember. Hold the transistor in yourfingers with the flat face toward you. Think of ahigh mountain in the rugged back country ofBritish Columbia—a cliff face reaching skyward.Now, reading left to right, whisper “Enjoy BritishLesson 9 ■Introducing Transistors 31NO TEFigure L9-1Figure L9-2Figure L9-3