Design Project: Simple Component Curve-Tracer Circuit

Discrete Semiconductor Devices and Circuits

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  • Question 1

    What do each of the oscilloscope axes represent, in real-life terms (variables and units) when used in conjunction with this curve tracer circuit?

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  • Question 2

    What mode does the oscilloscope have to be set in, in order to use with this curve tracer circuit?

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  • Question 3

    If quantitative accuracy is desired from this curve tracing circuit, the shunt resistor should be precisely 1 kΩ in size. Explain how a precise shunt resistance may be built without the use of precision components (i.e. a special 1 kΩ precision resistor).

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  • Question 4

    When testing this circuit for the first time, the student connects a 1 kΩ resistor to the two test leads and gets this result from the oscilloscope display:

    The student was actually expecting something that looked like this:

    Upon inspection, nothing appears to be wrong with the wiring of the curve tracer circuit. Explain what the problem is so the student is able to achieve the expected results.

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  • Question 5

    Explain why the wave-shape of the excitation voltage is irrelevant to the operation of this curve tracing circuit. The transformer happens to output the same sine wave shape exhibited by the AC line power, but the circuit would work equally wall with a triangle wave, sawtooth wave, or badly distorted sine wave.

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