20.309: Biological Instrumentation and Measurement
Photo by Brendan DolanGavitt
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 miniproject instead of this assignment.
Assignment Details
This assignment has three parts:
 Part 1: A few questions to answer before you start your lab work.;
 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:
 answers to the prelab questions
 answers to the following voltage divider questions:
 Record the values you selected for R_{1} and R_{2}.
 Find the gain of the circuit, $ ^{V_{out}}/_{V_{in}} $
 Plot an IV curve with I on the vertical axis and V_{in} on the horizontal axis, over the range 0 V < V_{in} < 15 V. (A handdrawn plot is fine.)
 What is the maximum power dissipated in each resistor between 0 V < V_{in} < 15 V?
 the measured values of your resistors.
 your measured voltages V_{out} for V_{in} = 0, 2.5, 5, 10 and 15 V.
 your measured voltage across R_{2} in the presence of the 1kΩ resistor. By what percentage did the measurement change?
 Recorded values of the current through the circuit for V_{in} = 0, 2.5, 5, 10 and 15 V
 A plot of the measured IV curve on the same set of axes as the calculated curve.
 your choice of capacitor and resistor values and corresponding Bode plot. Make sure to label the cutoff frequency.
 a plot of the measured values of $ \frac{V_{out}}{V_{in}} $ versus frequency on the same set of axes as your Bode plot.
 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.

Navigation
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Background Reading