NPN Foundations of Technology NPN © 2013 International Technology and Engineering Educators Association, STEM Center for Teaching and Learning™ Foundations
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Foundations of Technology
NPN 2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning Foundations of Technology Teacher Resource Unit 4 Lesson 4
2013 International Technology and Engineering Educators Association, STEMCenter for Teaching and Learning Foundations of Technology
Objective:You will build a simple circuit to show that a Negative-Positive-Negative (NPN) transistor will serve as a current amplifier.NPN2N3904CollectorBaseEmitterThe flat side faces up
You will need the following parts from your kit:Breadboard220 ohms resistor (red, red, brown, gold)3300 ohms resistor (orange, orange, red, gold)NPN Transistor2 @ LED (light emitting diode)9 volt battery lead3 wires9 volt batteryPushbutton switch
Use this schematic to construct the experiment. 220 Ohm+-9 voltsQuick Check: Your circuit should like this one.3.3K Ohmemittercollectorbase
This circuit will light the LEDs. Electrons will not flow through the emitter collector until there is current through the emitter base combination.This makes a small current control a large current which is referred to as amplification.An increase of current through the emitter base will result in a larger current through the emitter collector side of the circuit.If you change the 3.3K Ohm resistor you will see a change in LED brightness. You can also measure this with your Amp meter.
Connect the 9 volt battery.Observe the brightness of the LEDs.Press the pushbutton switch.Observe and compare the brightness of the LEDs.Release the pushbutton, both LEDs should turn off.Troubleshooting:If the LEDs do not light up, check to make sure they are in correctly.Check the battery. Does it have voltage?Are there any breaks in the circuit?Is the NPN in the right way?
By completing this experiment, you should have noticed the light from the LED on the emitter collector was brighter than the LED from the emitter base. The LEDs only light up after you press the button.In complete sentences, write what you learned about a NPN transistor in a circuit.
International Technology Education AssocSlide #*TITLE SLIDE12/01/2009STEMCenter for Teaching & Learning Engineering byDesign