ENGRMAE 106 Lecture Notes - Lecture 4: Breadboard, Crocodile Clip, Function Generator

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MAE106 Laboratory Exercises
Lab # 1 - Laboratory tools
University of California, Irvine
Department of Mechanical and Aerospace Engineering
To learn how to use the oscilloscope, function generator, breadboard, and potentiometer.
To learn how to use the Arduino microcontroller board.
Parts & equipment
Function generator (Trainer kit)
Seeduino board (Arduino)
The oscilloscope and function generator are useful tools for making measurements and
debugging machines. The solderless breadboard is useful for building circuits.
Potentiometers are common circuit elements to control voltages and measure rotations.
The Arduino board is a very useful microcontroller that provides an easy setup to control
electromechanical systems.
Note: When making electrical circuits in lab, a mistake in wiring may result in a component
getting "fried". If you smell something burning, immediately turn off your power supply and
debug your circuit.
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Part I: The oscilloscope and function generator (45 min.)
When you a building device, sometimes you want to be able to apply certain input voltages to
them. A function generator is a device that produces voltage waveforms such as sine, square,
and triangle waves, all with variable amplitude, frequency, and offset. For example, the
function generator can produce a voltage with the form:
  Equation 1
where the amplitude (), the frequency (), and the offset () are all adjustable.
When you build an electromechanical machine, such as a robot, you need to be able to
measure the voltages the device sends to different places so that you can debug your design.
A very useful tool for this purpose is an oscilloscope, which allows you to measure and view
voltage as a function of time.
Reading a Signal Using an Oscilloscope
Fig. 1: Oscilloscope. Important control knobs and on-screen information
1. Make sure that the oscilloscope CH 1 probe is connected to the output you want to read
and that the alligator clip is connected to ground. The multiplier on the oscilloscope probe
should be at the 1x setting.
Fig. 2: Function generator connected to Oscilloscope CH 1 probe (alligator clip goes to GND)
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2. Press the CH 1 MENU button (Fig. 1, green) and make sure that Coupling is set to DC.
3. Adjust sec/div (Fig. 1 blue), channel 1 volts/div (Fig. 1 yellow), and channel 1 vertical
position (Fig. 1 yellow), until you can see the yellow line (channel 1 signal) on screen.
4. Adjust the trigger level until it crosses the signal on screen. The trigger level is shown by
the little arrow on the right of the screen. Refine the scale and positioning settings until the
signal is shown as desired.
5. You can now read the signal by using the information on the screen. The yellow arrow on
the left of the screen corresponds to the ground level. The reading for C( at the bottom of
the screen corresponds to the number of Volts between horizontal lines. M corresponds to
the amount of time between vertical lines. Using this information, you should be able to
extract the main features of the signal (peak to peak voltage, frequency, DC offset, etc).
Practical Exam # 1
Use the function generator to create a 100Hz sine wave with a 1-volt amplitude and
zero DC offset. Using Equation 1, write down the mathematical formula for this wave
and label its components (amplitude, offset, and frequency). Finally, display this wave
in the oscilloscope and show it to your TA along with the mathematical formula (with
labels) describing the wave.
A Word about Breadboards
You will use an electronic breadboard (solderless breadboard) to wire up temporary
circuits as you build different devices you design. Electronic components and wires are
inserted into the numerous sockets (holes) on the board. The sockets (dots) are connected
internally (lines) as shown in Figure 2. A good method for wiring complicated circuits is to
connect the source voltage (+5V, 15 V) and ground terminals from the trainer kit to the long
narrow horizontal strips (Figure 2). The electronic chips you place on the board now have
ready access to power through short wires to sockets along the long strips. After wiring a
circuit to the solderless board, the oscilloscope is useful for measuring voltages at various
points on the circuit, by using one of the scope probes.
Fig. 3 Solderless Breadboard
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