ECED3201_Lab1_F2023_Rubric

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Dalhousie University *

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3201

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Electrical Engineering

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Dec 6, 2023

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ECED 3201: Introduction to Electronics Fall 2023 1 ECED 3201 Introduction to Electronics - Fall 2023 LAB #1 – The Semiconductor Diode Basics Marking Rubric Introduction 0.5 Q1. 2 Q2. 2 Q3. 1 Q4. 2 Q5. 2 Q6. 2 Q7. 2 Q8. 2 Q9. 2 Q10. 2 Conclusion 0.5 Total 20/20 General Notes: • Reports should be well formatted, with a suitable font / size and using appropriate technical writing, and graphs should have / axes / units labelled, and pictures of scope signals should be clear. • Answers can be short if they provide enough information to either answer a question or draw a suitable conclusion. • Students were given a lot of choice as far as the number of data points to measure, and specific resistor values to use. This will cause all reports to have similar, but different voltage / current measurements. • The priority for marking is that students are observing the data and making conclusions. • If the data collected was wrong, but they observe that and comment on it, that question can be awarded up to 100%. However, any lab with incorrect data collected can only get a maximum of 90%. Introduction (/0.5) • Students should have something written about the purpose of the lab, it can include anything referring to diode measurements, rectifiers, RC-Time constants. If it is well- written, and contains some technical content, they get full marks. Q1- Measure I D for different values of V D and sketch the transfer function I D vs V D in your report. (/2) • Students get 1 point for a graph showing the transfer function of the Si Diode, and Schottky Diode for a total of 2 points. Graphs must have suitable title and axes labeled. Q2- Find the equation of the obtained curve and deduce the value of the saturation current Is. (/2) • Students should have used an exponential line-of-best-fit tool for the equation and should say what the saturation (𝐼 𝑠 ) is. 1 point for the Si Diode, and 1 point for the Schottky diode. I’m not too concerned with if the value is correct, just that they extract the value from the line of best fit. This might appear on the graph in Q1.

ECED 3201: Introduction to Electronics Fall 2023 2 • Si-diode should be between 1E-08 -> 1E-12, and Schottky 1E-05 -> 1E-07. Here is an example of how it can be found, this was done using simulation: Q3- Compare Si and Schottky diodes in the forward and the reversed bias regions. (/1) • Students may or may not have a graph showing the RB region. If they do not, they should make a comparison using a datasheet / online resource they have found. • Students get 0.5 marks for comparing the FB regions, specifically the 𝑉 𝐷 & 𝐼 𝑠 values. They need at least 1 comparison between diodes. Comparisons must be based on data. • Students get 0.5 marks for comparing the RB regions, specifically leakage current. Comparisons must be supported with their data or a datasheet. 1. Circuits Using Silicon (Si) Diode Q4- Connect a Si diode in series with a 1 KΩ load resistor RL (using a 10 KΩ potentiometer) as shown in Fig. 2. Apply at VS a sinusoidal signal of 10 Vpp at 200 Hz. Observe and record (take a snapshot from the scope) the waveform of VS and VL and explain the operation of this circuit. (/2) • Students get 1 mark for having a scope picture showing a sin wave as the input, and a half-wave as the output since this is a half-wave rectifier. Amplitudes may vary, but if it is a sin input, and half-wave output, it is a full mark. • Students get 1 mark for describing the operation of the half-wave rectifier. Q5- Connect now a 1  F capacitor, CL, in parallel with RL in Fig 2 and observe, and record the waveform of VL. Change RL from 1 KΩ to 10 KΩ and observe the effect on the waveform of VL. Explain how the output is affected by the time constant RLCL. (/2) • Students get 1.5 points for having a minimum of two graphs. These graphs should show a sin wave input, and then a decaying positive half-cycle. There should be some difference in decay time from graph 1-2 and more graphs is fine. Below is a simulation showing what one of the graphs could look like. • Students get 0.5 point for explaining that the larger the RC-time constant as 𝑅 𝐿 increases, the longer the decay period is.

ECED 3201: Introduction to Electronics Fall 2023 3 Q6- Construct the circuit shown in Fig.3 using Si diodes. Apply at vS a sinusoidal signal with frequency of 200 Hz with 16Vpp and DC offset = 0V. Record the waveforms of v s and vO in your report and describe the functionality of this circuit. (/2) • Students get 1 point for having a scope graph like the simulation one below. It should have 3 distinct regions; 1 where the output is lower than the input, 1 where output = input, and 1 where the signal is clipped. As long as 2/3 of regions are correct, they get full points. • Students get 1 point for identifying the regions and discussing the graph. Q7- Use the instructions in Appendix B to plot v S versus v O on your scope and take snapshot for your report. Verify the obtained results using hand calculation. (/2) • Students get 1 point for having a graph similar to the simulation graph shown below. It just needs the right 3 distinct regions. • Students get 1 point for showing hand-calculations resulting in the correct transfer function as shown below. I can clarify calculations if required.

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ECED 3201: Introduction to Electronics Fall 2023 4 2. I vs. V characteristics of Zener diode Construct the circuit shown in Figure 1 using Zener diode now. Q8- Measure both the forward and reverse I-V characteristics of the Zener diode. Select value for the resistor R1 when measuring these characteristics so as to keep the diode current below 30 mA. (/2) • Students get 1 mark for part of the graph showing the FB region which looks like a normal diode. This complete graph is shown below from a simulation. • Students get 1 mark for part of the graph showing the RB region. This region is at ~6.5V. Q9- Find the equation of the obtained curve when the diode is in the breakdown region and estimate the value of the resistance ? 𝑍 . (/2) • Students get 1 mark for a line of best fit to estimate the incremental resistance ? 𝑍 . • Students get 1 mark for finding ? 𝑍 ; this process is shown in the simulation graph below. Student values may be different.

ECED 3201: Introduction to Electronics Fall 2023 5 3. Zener Diode Circuits Q10 - Construct the circuit shown in Fig. 4 using a Zener diode. Vary VS for 0 to 12 Vdc and observe and plot VO as a function of V S . Draw a conclusion. (/2) • Students get 1.5 marks for showing a graph plotting 𝑉 𝑂 𝑣? 𝑉 𝑠 , and identifying that the output voltage is constant once 𝑉 𝑂 ≅ 6.5𝑉 . • Student should make a conclusion about the Zener diode acting as a regulator / having a Zener voltage of 6.5V. Conclusion (/0.5) • Students should write a summary of some information. They get full marks if it has some technical content, talks about some parts of the lab, and is well-written. Marks should mostly be deducted for poor technical writing, or if the conclusion doesn’t talk about the lab at all.