Lab_1_-_Diodes_LEDs_Clipper_Simulation_1

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Jan 9, 2024

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CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation NAME: Jonathan Cerniaz POSSIBLE POINTS: 10 STUDENT ID: 028482153 COURSE DATE & TIME: August 29, 2022 Part 1 – LEDs (Light Emitting Diodes) Use the Benchtop Variable Power Supplies and the provided LED to connect the following circuit. Turn on the Benchtop Variable Power Supply using the smallest voltage that the PSU (Power Supply Unit can produce. Start at 0v and try to go up to 5v. Fill out the following table as you increase your voltage. Use a Multimeter to double check the voltage being displayed on the bench PSU. Vs It VD VR1 Apparent Brightness 1.30V 0.00A 1.3V 0V No light 1.50V 0.00A 1.5V 0V No light 1.75V 0.00A 1.7V 0V No light 2.00V 0.002A 1.76V 0.24V Dim 2.50V 0.0068A 1.81V 0.69V Bright 3.00V 0.0018A 1.8V 1.17V Bright 5.00V 0.0031A 1.9V 3.1V Very Bright

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation For the following questions, use the data gathered above and the datasheet found on the course website. 1.) LED’s are Current or Voltage driven devices? - LEDs are Current driven devices. 2.) Why did the LED get brighter when the voltage was increased? - The LED got brighter when the voltage was increased because and as current increased LED’s are current driven devices, so with more current the LED will become brighter as a result. 3.) Write a simple one sentence description of what it means for an LED to be Current or Voltage driven. - LEDs are current driven devices, so with more current the LED will become brighter as a result. 4.) What is Vf according to the datasheet? - 1.8V-2.2V 5.) What was Vf according to your test? - 1.8V 6.) What is the max current that the LED should ever have through it according to the datasheet? - According to the datasheet the peak forward current that the LED shoulder ever have through it is 30mA. 7.) Try adjusting the voltage until you get 30ma through the LED. Look directly at the LED from the top of it, notice that not only is it really bright but that the shape is designed as a lense to focus the light. Now adjust the current back down to what you think is a usable brightness for the LED (this is 100% subjective). What is the current at the useable brightness? - .20mA is a usable brightness, I think that its bright enough to do it job and its plays it safe from going above the peak forward current, which will keep it from getting damaged. 8.) (True/ False ) It’s ok to sometimes use an LED without a resistor. If you answered True, please explain… - False, it is not ok to use an LED without a resistor because you need some type of resistance to keep it from breaking the LED.

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation Part 2 – Diode Clipper Circuits Use LTSpice to model the following circuit and answer the questions. For calculations assume: Germanium Diodes have a typical Forward Voltage - V F = 0.3v Silicon Diodes have a typical V F = 0.7v LEDs and other specialized diodes have V F = 1.2 to 3.3v and even greater sometimes 1a) V S = 5v, D is a 1n4001, R = 1k How is the diode biased?: Forward Biased Calculate V D (show equation if it exists): Vd = Vf Calculate V R (show equation if it exists): Vr =V-Vd Measure V D : 0.7V Measure V R : 4.3V Does V D = V F , Why? Yes, because silicon diodes have a typical voltage of 0.7V and 1n4001 is a silicon diode so they both should have the same voltage going across it. Include a Screen Capture of your LTSpice model with both measured values shown on the graph

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CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation 1b) V S = 5v, D is a 1n4001, R = 1k How is the diode biased?: Reverse Biased Redraw the Schematic by hand using the 1 st approximation (i.e. Ideal Diode V F = 0v) Calculate V D (show equation if it exists): Calculate V R (show equation if it exists): LTSpice Measurement of V D : 5V LTSpice Measurement of V R : 0V Does V D = V F , Why? Since the diode is reversed biased, it acts like an open switch so it will not conduct, meaning that VD will not be able Vf. Include a Screen Capture of your LTSpice model with both measured values shown on the graph

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation LTSpice Screenshot and Write-Up Requirements: • For the following circuits, include a Screen Capture of your LTSpice model with all measured max and min values annotated on the waveform. You may edit the image and add them or draw them in with pencil after printing, it’s your choice. In other words, you should take a screenshot of the waveform, then use the built in LTSpice waveform measurement tools to measure the min and max voltage for V AC, V R, V D, Vout and annotate the screenshot with those values. In the following circuits, Vout will be equal to V D or V R, In these instances you can just draw a line and label the voltage as: max Vout = V R = 3v, or min Vout = V R = 3v. • In LTSpice be sure to label the nets with Vin and Vout. • In LTSpice, you can take measurements by clicking on the net name in the waveform. You can then hover the mouse over the intersection/crosshairs, left click and drag so you can measure the values at different time points.

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation 2a) Series Diode Clipper: Vac = 6V pk-pk , Fac = 1Khz, D = 1n4001, R = 27K LTSpice Measurements, V AC Pk-Pk : 3V V R Pk-Pk : 2.5V V D Pk-Pk : 3.5V Include a Screen Capture of your LTSpice model with all measured values shown on the graph Draw the waveform, label and include V AC and Vout/V R Calculate V AC in pk - pk voltage? 6V Calculate V R in pk - pk voltage? 2.5V Calculate V D in pk - pk voltage? 3.5V Is this negative or positive clipping? - Negative clipping

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CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation 2b) Series Diode Clipper: V ac = 6V pk-pk , D = 1n4001, R = 27K LTSpice Measurements, V AC Pk-Pk : 6V V R Pk-Pk : 2.5V V D Pk-Pk : 3.5V Include a Screen Capture of your LTSpice model with all measured values shown on the graph Draw the wavef orm, label and include V AC and Vout/V R Calculate V AC in pk - pk voltage? 6 V Calculate V R in pk - pk voltage? 2.5V Calculate V D in pk - pk voltage? 3.5V Is this negative or positive clipping? - Positive clipping

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation 3a) Shunt Diode Clipper: V ac = 6V pk-pk , D = 1n4001, R = 27K LTSpice Measurements, V AC Pk-Pk : 3V V R Pk-Pk : 3.4V V D Pk-Pk : 2.6V Include a Screen Capture of your LTSpice model with all measured values shown on the graph Draw the waveform, label and include V AC and Vout/V D Calculate V AC in pk - pk voltage ? 3V Calculate V R in pk - pk voltage? 3.4V Calculate V D in pk - pk voltage? 2.6V Is this negative or positive clipping? - Positive clipping

CECS 311 - LAB 1 – Diodes Diodes: LEDs and Clipper Circuit Simulation 3b) Shunt Diode Clipper: V ac = 6V pk-pk , D = 1n4001, R = 27K LTSpice Measurements, V AC Pk-Pk : 6V V R Pk-Pk : 2.6V V D Pk-Pk : 3.4V Include a Screen Capture of your LTSpice model with all measured values shown on the graph. Draw the waveform, label and include V AC and Vout/V D What is V AC in pk - pk voltage? 6 V What is V R in pk - pk voltage? 2.6V What is V D in pk - pk voltage? 3.4V Is this n egative or positive clipping? - Negative clipping

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