Labs

 Electrical Engineering is about 'what can you do to a voltage'? Throughout the semester, we will be learning about many different ways to control the voltage and current in a circuit.  For example, voltage and current dividers split (or add) voltages and currents, amplifiers increase (or decrease) them, inverters reverse their polarity (multiply by -1) and more.  Each lab will provide you with a set of skills (such as how to measure V,I,R, design and specify the correct parts, build and test circuits, and more).  The overall labs this semester will focus on resistive and capacitive sensors.  Resistance and capacitance can be used to measure temperature, pressure, proximity, moisture, and more. They basically take data from the outside world.  The circuits we connect them to will give information back to us (such as turning on a light if something gets too hot).  At the end of the semester, you will be ready to build a resistive or capacitive sensor system of your own design, and the last 2 weeks of lab will be a Rube Goldberg Links to an external site.  to build a sensor to do SOMETHING, anything!  You choose, you design, you build.  This can be relatively simple, using the concepts from the labs in class (and yes, that is sufficient to do well in the lab).  Or, this can be as advanced as you would like to make it.  So, as you move throughout the labs this semester, start to think about ways you might use the circuits and concepts from each lab and combine them into a sensing system for SOMETHING....

Let's get started:

SKILLS you will develop in each lab are in Yellow.

TOOLS you will use are in BLUE.

STUFF you will build are in PINK

Multisim V-R in series  (50 points) Simulate a very simple V-R circuit with multisim.  The most important thing about this assignment is getting Multisim running on your computer.  You will learn the basics of putting down circuit elements, simulating the circuit response, and 'measuring' voltage and current in Multisim.  I hope you are also familiar with the online resources for Multisim including tutorials, etc.  You will use these resources throughout the semester.

Multisim 3way switch (50 points) Simulate a 3-way switch with multisim.  You will explore a few more circuit elements (switches and bulbs), and see how Multisim simulates the action of the circuit (not just V and I measurements).  It is also a cool puzzle to think through how a 3-way switch works in your house.  By the end of this assignment, I hope you are pretty comfortable with Multisim.

Lab 1 -- Measuring Resistance and Resistive Networks:  We will be measuring resistive networks and setting up/measuring two potentiometers in series. This most important thing about this lab is getting the MyDAQ running on your computer and acquire the basic components for building a circuit (protoboard, wires, resistors, pots).  You will then use the MyDAQ to explore and verify simple resistive networks, and the potentiometers.  Another important skill and understanding from this lab is being able to use the protoboard to build your circuit (in this case, the pots in series).  Upcoming: ( In Lab 2, this connection of pots will be used as a variable resistance to test a resistance indicator, and in Lab 3, they will be used as a tuner for a variable voltage source.)

Lab 2 -- Voltage, Current & Resistance.  In this lab you will measure voltage and infer current from voltage measurements.  You will Calculate, Simulate, Build, Test (and compare these) for a serial/parallel resistive network, and voltage and current dividers.  You will also design and build a resistance indicator (a light that will go on/off depending on the resistance).  We will later use this same concept to build a voltage indicator for our variable voltage source.  Beginning debug skills.

Lab 3 -- Resistive Sensors and Variable Voltage Source.   In this lab, you will build a variable voltage source for the MyDAQ using a variable resistance (tuned by the two pots in series from Lab 1), and build a voltage indicator (using the same concept as the resistance indicator from Lab2) to turn on lights, depending on what your voltage is.  

Lab 4 --Resistive Sensors You will experiment with a thermistor (resistance changes with temperature), photoresistor, (reistance changes with light) and home-made graphite moisture sensor (resistance changes with moisture and graphite pattern).  You will build an op amp switch to turn a light on/off depending on the resistance (and its associated temp, light, moisture) and an op amp inverting amplifier to change voltage depending on the resistance.  Extra credit in this lab is to design your own resistive sensor system.

Matlab (will be assigned as homework, but will be added in to the LAB grade instead of the homework grade).    TAs will be available during lab times to help you with your Matlab homework and answer any questions as you study for the exam.  Use Matlab to solve many of the same types of circuit problems you have been doing for your homework.  Basic math, matrix math, plotting (your thermistor data), curve fitting. The Matlab homework is also meant to be review for the midterm, at least in part.

Lab 5 -- Op Amp Digital to Analog (D/A) converter 

Lab 6 -- Digital Candle + Matlab

Lab 7 -- Capacitive Sensors.  In this lab you will build and test  capacitive sensors. 

Lab 8 (3 weeks) -- Invent a Sensor System. Design, simulate, and build a sensor system of your own devising.  Choose and/or build an R or C sensor. Build the circuit to have this sensor do something.  It can turn on a light, motor, or buzzer, for instance.