Assignment 6 Overview

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20.309: Biological Instrumentation and Measurement

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During the next few weeks in lab, you will build and debug several electronic circuits to measure melting curves of DNA. This assignment will introduce you to the electronic components and test equipment you will use. This assignment requires an understanding of basic circuits. If you need to review circuit concepts, start with the Electronics Primer page. If you have a lot of experience with electronics, ask one of the instructors about doing a stimulating mini-project instead of this assignment.

Assignment Details

This assignment has three parts:

  1. Part 1: A few questions to answer before you start your lab work.;
  2. Part 2: Get in the lab and start building and measuring basic circuits;

Submit your work on Stellar in a single PDF file with the naming convention <Lastname><Firstname>Assignment6.pdf.


Here is a checklist of all things you have to turn in: (individually)

  1. answers to the prelab questions
  2. answers to the following voltage divider questions:
    • Record the values you selected for R1 and R2.
    • Find the gain of the circuit, $ ^{V_{out}}/_{V_{in}} $
    • Plot an I-V curve with I on the vertical axis and Vin on the horizontal axis, over the range 0 V < Vin < 15 V. (A hand-drawn plot is fine.)
    • What is the maximum power dissipated in each resistor between 0 V < Vin < 15 V?
  3. the measured values of your resistors.
  4. your measured voltages Vout for Vin = 0, 2.5, 5, 10 and 15 V.
  5. your measured voltage across R2 in the presence of the 1kΩ resistor. By what percentage did the measurement change?
  6. Recorded values of the current through the circuit for Vin = 0, 2.5, 5, 10 and 15 V
  7. A plot of the measured I-V curve on the same set of axes as the calculated curve.
  8. your choice of capacitor and resistor values and corresponding Bode plot. Make sure to label the cutoff frequency.
  9. a plot of the measured values of $ \frac{V_{out}}{V_{in}} $ versus frequency on the same set of axes as your Bode plot.
  10. your Bode gain and phase plots and the corresponding circuit diagram for each of the four circuits A through D. Optional: In Matlab, use nlinfit to fit parameters of a transfer function for each circuit.


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