Description
please mark all the current and voltage directions
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MAE 3780
Problems
1. Sources (ungraded, required)
a. List names of all people you worked with on the homework.
b. List all places you got help or found information (Piazza, office hours, course notes,
textbook, websites, etc.).
2. Find VOUT in the following circuit:
3. Given the following graph for VS, plot Vout(t) for each of the following circuits. R=2kΩ,
RL=100Ω, C=3µF
MAE 3780
4. In the following circuit, Vs(t) is a sinusoidal voltage input. Find
filter. What type of filter is it?
and the gain of the
5. Find the datasheet for the TL081C op-amp on Canvas.
a. What are the absolute maximum/minimum supply voltages?
b. What is the input resistance?
c. What is the definition of “slew rate” for an op amp?
d. What is the typical slew rate for the TL081C?
READ THESE INSTRUCTIONS CAREFULLY BEFORE YOU START
Before you start building functional op-amp circuits, make sure you understand how to use your opamp on a breadboard and power it. Watch this video about building an op-amp circuit from a circuit
diagram. Be careful not to get the circuit diagram symbol for an op-amp mixed up with the physical
layout of the pins on the integrated circuit (IC). The latter is what you physically put in the
breadboard. In this assignment you will not use the OFFSET N1, OFFSET N2, or NC pins. You
will leave them disconnected.
MAE 3780
7. (Kit problem) Select resistor values R and RF for a non-inverting amplifier (pictured
below) such that the output voltage has triple the amplitude of the input voltage. You must
use resistors in your kit, but remember that you can combine resistors in series and parallel
to create other resistance values. Make sure both resistors are at least 10kΩ.
a. What are your values for R and RF?
b. Build the circuit and set VS to a 1kHz triangle wave. What are your measured peakto-peak voltages for VS and VOUT?
c. Submit a screenshot that shows at least two periods of both the input and output
voltages.
MAE 3780
8. Sometimes you might need to measure a very small difference between two voltages (for
example, from the strain gauge you saw on an earlier homework assignment and may have
learned about in MAE 3270). In that case, it may be useful to amplify the voltage difference
first, to make it easier to measure. The following circuit is called a differential amplifier and
is used for this purpose. Find an expression for V OUT as a function of the resistances and
input voltages. Show your work.
9. (Kit problem) In this problem you will analyze and build an active low-pass filter (shown
below).
MAE 3780
a. Write an expression for the magnitude of the circuit’s frequency response,
|VOUT/VS|. You do not have to show your work if you have the equations in your
notes.
b. If RF = 100kΩ and CF = 0.01µF, choose a value for RS such that the maximum value
of the magnitude of the frequency response is |V OUT/VS|= 2.
c. Build the circuit using the resistor and capacitor values from part b. Perform a
frequency sweep using your oscilloscope, with a sine wave ranging from 10Hz to
10kHz. At each frequency, use the oscilloscope’s automatic measurement function to
measure the peak-to-peak voltage of the output. Submit a graph showing both the
experimental and theoretical frequency responses, with |V OUT/VS| on the y-axis and
frequency in Hz on the x-axis on a logarithmic scale.
d. Compare your graph from part d to your graph for the low-pass filter from
homework 3. What are the main differences between the plots?
10. Does Tinkercad simulate an “ideal” op amp or does it place practical limitations on the op
amp’s behavior? Find out!. You do not need to submit a link to a circuit for this part, just
provide written answers for each question.
a. What happens if you adjust the inputs such that the output voltage should be greater
than the power supply voltage? Does Tinkercad let the output exceed the power
supply?
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