EMT 1255 Electronics lab Diode Characteristics PDF

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EXPERIMENT “The Diode Characteristics”  EMT 1255 OL26 ELECTRONICS LAB REPORT   NEW YORK CITY COLLEGE OF TECHNOLOGY 

 DEPARTMENT OF COMPUTER ENGINEERING TECHNOLOGY FALL 2020

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EMT 1255 OL26 LAB REPORT

Experiment # 2

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Fahmeda Khanom

Prof. Abdulfattah Mustapha

Date of the experiment: 9/15/2020 Due Date: 9/21/2020

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 Table of Contents  Objective..……………………………………………………………….page 4 Materials used…………………………………………………………..page 4 Procedure……………………………………………………………page 4-5 Data…………………………………………………………………page 5-6 Figure……………………………………………………………page 6-8 Sample Calculations…………………………………………..Page 8-9 Conclusion and Discussion………………………………………page 9 Questions…………………………………………………………..page 9-10

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Objective The main aim of the experiment is to measure and plot forward and reversed characteristics of the diode in the graph. Also, measure the diode using the ohmmeter and to measure the ac resistance of a diode. Equipment and Materials 1. Multisim 2. Function Generator 3. Oscilloscope 4. Resistor 330 Ω 5. Resistor 1.0 M Ω 6. Diode 1N914 7. DC Power 8. Multimeter

Procedure 1. For the lab, I did Multisim and form the circuit using the Multisim components 2. First, I place all the components I need from Multisim components such as resistors, DC Power, multimeter, ground, and diode. 3. Then, I connect the wires of the resistors to the diode and diode to the voltage source and back to the resistor. Then placed the multimeter across the resistor, diode, and voltage source. 4. Also, we change the value of Vs to get the voltage across the diode to be .45 volts for the first data in the experiment. 5. In the experiment, we use a multimeter to measure the value of the resistor and the value of the diode. 6. For the second circuit in the second figure of the experiment, I replace the resistor 330 ohm to 1.0 M ohm and had the same procedure as figure 1. I also change the value of Vs to get the value close to 5 V for the first data in figure 2. 7. For the figure 3 circuit, I used an oscilloscope and function generator along with a

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330-ohm resistor. Moreover, I used a diode that was ground with a resistor and oscilloscope. 8. Then, we plot the reverse and forward-biased diode curves.

DATA Resistor

Listed value

Measured Value

R1

330 Ω 

330 Ω 

R2

1.0 M Ω 

1.0 M Ω 

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D1 forward resistance

.590 V

D1 reverse resistance

0V

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VF

V R1

IF

.45 V

1.187 mV

3.59 μ A

.50 V

9.185 mV

.027 mA

.55 V

53.428 mV

.169 mA

.60 V

354.058 mV

.00107 A

.65 V

1.9 V

.005 A

.70 V

6V

0.01818 A

.75 V

12.48 V

0.037818 A

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V R2

VR

IR

5V

5.056 mV

5.056 nA

10 V

10.015 mV

10.015 nA

15 V

15.018 mV

15.018 nA

Figure 

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Sample Calculations Calculation of Figure 1

a)

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1.985 mV 330 Ω

= 3.59 μA

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b)

9.185 mV 330 Ω

= 0.027 mA

c)

53.429 mV 330 Ω

= .169 mA

Calculation of figure 2

a) b) c)

5.056 mV = 5.056 nA 1 MΩ 10.015 mV = 10.015 nA 330 Ω 15.018 mV = 15.018 nA 330 Ω

Conclusions In conclusion, the lab was very effective to learn how to build a circuit. In the forest circuit for figure 1 we have a 330-ohm resistor and we keep increasing the value of Vs to get a certain value given on the manual for the voltage across the diode. Next, we replace the value of the diode and also reverse the diode to measure the values. The circuit in multisim helps a lot to analyze the significance of each component and the results we get after building a circuit using the components.

Questions 1. What factors affected the accuracy of the measurements in these experiments? (Consider both the forward-biased and reverse-biased cases.) Answer: The factors that affected the accuracy of the experiment were that the resistance value across the diode was given in megaohms and then to calculate the current was confusing to me and also affected the accuracy of the experiment. 2. Compute the diode’s ac resistance at three points on the forward-biased curve. Apply Ohm’s law to the curve in Plot 2-1 at 0.5 V, and 0.7 V by dividing a small change in voltage by a small change in current, as illustrated in Figure 2-2. R(ac)(0.5 V)= 336.5 Ω

R(ac)(0.6 V)= 331 Ω

R(ac)(0.7 V)= 330.1 Ω

3) From the data in Table 2-2, compute the maximum power dissipated in the diode. P = IV P = .75 V x 12.85 mA = 9.64 mW 

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4)Explain how you could use an ohmmeter to identify the cathode of an unmarked diode. Why is it necessary to know the actual polarity of the ohmmeter leads? Answer: Cathode has the least resistance and is negative and the anode is the most resistant and is positive. It is important to know the polarity because the negative terminal has to be with the cathode and the positive terminal need to be with the anode.

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