M2_Studio_DiodesRectifiers

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University of Virginia *

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2600

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Electrical Engineering

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Dec 6, 2023

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ECE 2600 – Electronics Studio 2: Diodes & Rectifiers Introduction In the studio for this module, you will examine diode I-V characteristics, as well as build and test various different rectifier circuits. Every student must layout a board, prototype the circuit, and gather their own experimental data, which should then be synthesized into an individual studio write-up. You are encouraged to work with other students to help your understanding, but you should still be collecting your own data. The students you work with should be the first people you ask any questions before you ask an instructor or TA. Your write-up must follow the format of the lab. For clarity, outputs from the studio that need to be included in your report will be highlighted in yellow. When you have reached the “ SIGN OFF ” text, have a TA or instructor come sign off that it has been completed. You can be signed off if your measurement is complete, and you will be expected to answer a question to check your understanding of the concepts covered in the studio. In your report, be sure to include units and to caption all figures and tables. All figures should be legible at normal zoom levels. Studio 2.1 – Diode I-V Characteristics Your report for part 2.1 should start on a new page. In this studio activity, you will construct a diode rectifier to observe the diode characteristics in forward- and reverse-biased modes. In your kit, you may have a 1N4001 rather than a 1N4148. You may use either, but in your report, indicate which of the two you use. 2.1a: Analysis and Design 1) Simulate the circuit in Fig. 1 in Multisim, and plot its forward- and reverse-biased curves by varying the input from -4.5 to 4.5 V (use a DC sweep, with V1 as a DC voltage source). 2) Export the data and plot the IV curve for the diode for both an analytical solution and simulated solution. You may write your own code or use the provided Python template. In your report, include this plot, with an appropriate caption. Fig. 1. Schematic for a basic rectifier circuit.

ECE 2600 – Electronics 3) Plot the transient for a sinusoidal input, with frequency 𝑓 = 1 kHz, and amplitude 3 V. Observe the input voltage, voltage drop across the diode, and/or voltage drop across the resistor. In your report, include this plot and record your observations. 2.1b: Hands-On Activities For the hands-on activities, you will want to reference the datasheets for the diodes. These are available at the following links: - 1N4001 : https://rocelec.widen.net/view/pdf/3zl1amyajw/FAIR-S-A0002364504- 1.pdf?t.download=true&u=5oefqw - 1N4148 : https://www.onsemi.com/download/data-sheet/pdf/1n914-d.pdf 1) Build the circuit shown in Figure 1 on your breadboard. Connect scope channel 1 to the input, and scope channel 2 to the output. 2) Set the input to be a sine wave with 3.5 V amplitude and frequency 200 Hz. Screenshot the input and output on the same oscilloscope window. In your report, include these plots, and record the threshold voltage of the diode. 3) Set the input to a triangle wave, and sweep the input from -4.5 V to 4.5 V. Set the window to view one cycle of the input and output voltages. You may wish to save these plots for your own reference, but you do not need to include them in your report. a) Export this data to a .csv, and use the provided Python template to plot the I-V curve. b) In your report, include the final plot showing the current through the diode as a function of the voltage over the diode. 4) SIGN OFF 2.1c: Discussion Questions In your report, answer the following questions: 1) What do you observe happening to the forward bias and reverse bias characteristics of the diode as the input voltage varies? You may refer to any of the diodes for this explanation, and do not need to discuss differences between the diodes. Explain what is occurring intuitively, using the threshold voltage model of the diode.

ECE 2600 – Electronics Studio 2.2 – LED Characterization Your report for part 2.2 should start on a new page. In this studio activity, you will explore the I-V characteristics for two LEDs, one red and one green, which you will eventually want to use for your project. 2.2a: Analysis & Design There is no additional analysis & design for this activity. In your report , include “N/A” for this section. 2.2b: Hands-On Activities You will want to reference the datasheets for the two diodes, available at the following links: - Red LED : https://media.digikey.com/pdf/Data%20Sheets/Avago%20PDFs/HLMP- 47zz,HLMP-17zz_2021-08-09.pdf - Green LED : https://www.vishay.com/docs/83006/tlhg440.pdf o Note: the green LED in your lab kit may be a different size than the one in the datasheet. You will characterize two diodes in this activity: a green LED and a red LED. For each LED you characterize: 1) Build the circuit shown in Figure 1 on your breadboard. Connect scope channel 1 to the input, and scope channel 2 to the output. 2) Set the input to be a sine wave with 3.5 V amplitude and frequency 200 Hz. Screenshot the input and output on the same oscilloscope window. In your report, include these plots, and record the threshold voltage of the diode. 3) Set the input to a triangle wave, and sweep the input from -4.5 V to 4.5 V. Set the window to view one cycle of the input and output voltages. You may wish to save these plots for your own reference, but you do not need to include them in your report. a) Export this data to a .csv, and use the provided Python template to plot the I-V curves. b) In your report, include the final plot showing the current through the diode as a function of the voltage over the diode for both diodes. In the caption, note the relative order of the threshold voltages for the diodes, and how that order is reflected in the plot. 4) SIGN OFF You may have noticed that your LEDs were not visible during your tests. This is because it is the current , not the voltage drop, that determines the brightness of an LED, and the large resistor is limiting the amount of current.

ECE 2600 – Electronics 5) Using the datasheet for your LEDs, look up the maximum current and divide this number in half (we do this to achieve a conservative design , to avoid being too close to the absolute maximum rating). 6) Design a new value for the resistor based on the following: a) The desired current level b) The expected voltage drop of the LEDs c) A maximum source voltage of 5 V. In your report, include this calculation, and an explanation for the values you used. 7) Using your designed resistance value, try inputting different voltages and see how your LEDs change brightness (be careful not to exceed your maximum current rating!). In your report, include a picture of your LEDs turned on, and indicate what experimental settings you had. 2.2c: Discussion Questions 1) How do the measured threshold voltages for the LEDs compare to the values presented in the datasheet? What might explain any differences in the measured and expected threshold voltages? Studio 2.3 – Half-Wave Rectifier FFT Your report for part 2.3 should start on a new page. In this studio activity, you will gain familiarity with numerical and experimental methods for estimating Fourier series coefficients. You will examine the Fourier series in further detail as part of ECE 2700 – Signals & Systems. 2.3a: Analysis and Design A function 𝑓(𝑡) may be defined as periodic if it meets the condition that 𝑓(𝑡 + 𝑛𝑇) = 𝑓(𝑡) for 𝑛 = 1,2,3 … for every t . Any periodic function that satisfies the following constraints can be represented as a sum of sines and cosines: - There are a finite number of minima and maxima within each cycle of the function - There are a finite number of discontinuities within each cycle of the function - Discontinuities must be bounded such that ∫ |𝑓(𝑡)|𝑑𝑡 𝑇 0 < ∞ The function can therefore be defined as 𝑓(𝑡) = ? 0 + ∑(? ? cos(𝜔 0 𝑛𝑡) + ? ? sin(𝜔 0 𝑛𝑡)) ∞ ?=1 ? 0 = 1 𝑇 ∫ 𝑓(𝑡)𝑑𝑡 𝑇 0

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