Electronics I Laboratory 2

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*      PNP Emitter Follower, Complementary Transistor Driver Experiment

*      Schematic of First Circuit To Be Built And Tested

*      Schematic of Second Circuit

PNP Emitter Follower, Complementary Transistor Driver Experiment

Tasks for this lab:

*      Build each circuit below using supplies from the lab, the Instructor, and the Technician. Use your lab kit from Networks I/II.

*      Test the circuits, and record the voltages at the base and emitter of the transistor when there is no signal applied.

*      Set up your signal generator for a sine wave output

*      Amplitude 1 volt peak

*      Frequency 1,000 Hz

*      Apply the signal generator output to the oscilloscope.

*      Save the plots for your lab report

*      Repeat for a 1 volt peak triangular wave at 1,000 Hz.

*      Repeat for a 1 volt peak square wave at 1,000 Hz.

*      Load the output with a 100 Ohm resistor.

*      Change the frequency of the signal generator to find the high and low frequency limits over which the output amplitude remains approximately constant.

*      Write a lab report. The lab report is due a week from Monday morning.

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Schematic of First Circuit To Be Built And Tested

Note that this circuit is similar but not identical to the circuit built for Laboratory 1. Leave the circuit for Laboratory 1 on the wireless prototype board because you will be using it with the first circuit for Laboratory 2 to build the second circuit.

 

Note that the emitter of the PNP transistor and the load resistor for it are hooked toward the +5 Volt power source, not ground. If you use a 2N3904 instead of a 2N4401 on the first experiment, use a 2N3906 for this circuit. This is recommended to match the transistors for the second circuit.

Figure 1. PNP Emitter Follower

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Schematic of Second Circuit

Note that most of the elements of both the NPN emitter follower circuit for Laboratory 1 and the PNP emitter follower circuit built as the first circuit of Laboratory 2 are used.

 

We will not have a 5 Ohm resistor rated at two watts available. Use four 20 Ohm Watt resistors in parallel to make up a 5 Ohm 2 Watt resistor.

Figure 2 Complementary Transistor Driver Circuit

 

Key things to look for in testing the second circuit are how much signal voltage is tolerated before the output is visibly distorted, and differences in the high and low frequency limits.

 

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