Chapter 1
Equipment Operation and Safety
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CHAPTER 1. EQUIPMENT OPERATION AND SAFETY
1.1
Section Overview
The purpose of this lab is to learn how to use the various hardware and software tools used in this course. In
addition, safety issues and usage guidelines for these pieces of test equipment will be covered.
1.2
Procedure
In this section, the following items will be covered.
1. Safety in the lab
2. Hardware tools
3. Software tools
1.3
Safety in the Lab
The following are important safety issues and warnings:
1. Whenever dealing with electronics or electricity, make sure there is no power going to the circuit when
modifying it.
2. To prevent shock (especially on high voltage devices) use only one hand to touch the circuit whenever possible.
Using two hands could allow electricity to pass through the body and heart. In these labs, the voltages and
currents used are not large enough for this to be a real risk, but it should be noted for later courses.
3. The circuits that created in this lab will need to be protected as well. Some of these components are very
sensitive and can be affected by static electricity. In order to prevent damage to these components, they are
placed in static bags or bins, which reduce the surrounding static electricity.
4. Static electricity builds up easily on the body, creating large voltages with little current. This voltage can destroy
the sensitive electronics in some components. Always handle electronics with a grounding strap attached to a
shoe or wrist.
5. If a circuit begins generating an excessive amount of heat, it could be due to a short circuit in the wiring.
Immediately remove the power and search for leads that are unintentionally touching.
6. Capacitors, even when disconnected from a circuit, may retain charge for a long period of time. They may
deliver a painful shock even without power. If uncertain whether a capacitor is still charged, hold a resistor
against the two contacts to discharge it.
7. Pay attention to the safety information discussed below for each individual piece of equipment. Note that some
electrical components, such as diodes, have polarity and must be oriented correctly in the circuit.
1.4
Hardware Tools
In this course, three major pieces of hardware will be used: the power supply, the digital multimeter (DMM), and the
oscilloscope.
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1.4. HARDWARE TOOLS
1.4.1
Power Supply
A power supply such as the Tektronix CPS250 gives an easy way of supplying voltage and current to circuits. Begin
by locating the power supply (shown in Figure 1.1), and turning it on. The power switch is located in the upper left
hand corner.
Figure 1.1: Tektronix CPS250 Power Supply
Follow these steps to adjust the power supply to output a specific value:
1. The power supply can deliver three different voltages at the same time: two adjustable and one fixed at 5V DC.
For this lab, use source A. Set the A/B meter switch to the A position, causing the meters (voltage and current)
to reflect the A channel values, not the B channel. In later labs it will be advantageous for each channel to
display a different voltage, so the channels need to be set to INDEPENDENT (see Figure 1.2).
Figure 1.2: Setting the power supply to output independently on channel A
2. Turn the voltage control knob for source A until the voltage meter displays 5V.
3. The current knob on the power supply must be set in a manner such that it is higher than the current in the
circuit to which it is hooked. Turn the current control for source A to the middle setting (as shown in Figure 1.3).
The supply should now be able to source about 300 mA.
The current needle will not move because the power supply is not connected to a load. The
‘CURRENT’ knob limits the amount of current that could be supplied to a circuit.
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Figure 1.3: Rotate the current knob for A into the middle
4. Before connecting the power supply to a device, examine the Channel A outputs (Figure 1.4). Notice the black
and red outputs labeled - and + respectively.
Figure 1.4: Power supply outputs
5. Using one test set of the black and red cables, shown in Figures 1.5, 1.6, and 1.7, connect the banana plugs to
the power supply outputs. Make sure to connect the red plug to the positive output, and the black plug to the
negative output. The power supply is now setup to have a device connected at 5V and approximately 300mA.
Figure 1.5: Cables for the power supply
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Figure 1.6: These are banana plugs
Figure 1.7: These are micro grabbers
1.4.2
Digital Multimeter
A digital multimeter (DMM) can be used to take measurements: the voltage across a component, the current flowing
through it, or the resistance. See Figure 1.8 for an illustration of the Fluke 45 multimeter, a machine in this lab.
Figure 1.8: This is a benchtop DMM
Using the DMM to measure voltage and resistance:
Locate the DMM similar to the one shown in Figure 1.8. Take a second set of black and red cables and insert the
black banana plug into the black COM (common ground) terminal in the DMM. Insert the red banana plug into the VΩ
plug. The terminals are shown in Figure 1.9. Now the DMM is ready to take voltage and resistance measurements.
Figure 1.9: These are the terminals on the DMM
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Use the DMM to measure voltage, follow these steps:
1. Find the voltage across the terminals of the power supply. Using the micrograbber ends of the cables from the
DMM and power supply, connect the red micrograbbers together by squeezing down on the back. Repeat with
the black micrograbbers. The DMM is now ready to measure the voltage across the terminals of the power
supply.
2. Turn on the DMM using the green button in the bottom right corner.
3. Set the DMM to measure the DC volts scale, but pushing the upper left button shown in Figure 1.9. It will have
a V and two parallel lines, one solid and one dashed.
4. Record the voltage reading here.
Use the DMM to measure resistance, follow these steps:
1. Set the DMM to measure resistance by pressing the button that has an Ohm symbol, Ω.
2. Connect the two micrograbber leads from the DMM across a resistor, shown in Figure 1.10.
Figure 1.11: This is how the micrograbbers can hold a resistor
Figure 1.10: These are resistors
3. Record the resistance reading here.
If the resistance is less than 100Ω, select a different resistor and remeasure.
Use the DMM to measure current, follow these steps:
1. Taking a current measurement requires a load to be connected in series with the DMM, This limits the amount
of current flowing through the circuit and prevents a blown fuse from reading an infinite current.
The DMM has a small fuse inside of it that will burn out it too much current passes through
the fuse.
2. Disconnect the micrograbbers from the DMM. It is always a good idea to disconnect the DMM from the project
when changing what is to be measured.
3. Set the multimeter to the DC current scale. Press the button directly to the right of the DC volts button. The DC
current scale should have an A with two parallel lines next to it.
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4. Many DMMs (including this one) require the probes to be connected in a different location on the DMM when
changing between voltage, resistance and current measurements. Move the red banana plug to the one
labeled ‘100 mA’ when taking current measurements as shown in Figure 1.12
Figure 1.12: Banana Plug configuration for measuring current
5. The power supply acts as a battery and pushes current through the resistor, which limits the current in the
circuit. The limited current passes through the DMM, is measured, and then allowed to flow back through to the
battery, thus completing the circuit.
6. Using the same resistor as in previous steps, connect the red micro-grabber from the power supply to one of
the resistor terminals and the red micro-grabber from the DMM to the other terminal. Then complete the circuit
by connecting the black micro-grabbers from the power supply and the DMM together. Turn on the power
supply. Use Figure 1.13 as a reference.
Figure 1.13: Micro-grabber connection for measuring current.
7. Record the current reading here.
1.4.3
Oscilloscope
Another tool for taking circuit measurements is the oscilloscope. Figure 1.14 shows the oscilloscope used in this lab,
the Tektronix TDS210.
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Figure 1.14: This is an oscilloscope
In this lab the oscilloscope will typically be used to monitor DC voltages that vary with time. The screen displays the
measured waveform as a function of voltage with respect to time. The scale can be adjusted using the VOLT/DIV
(Volts per division) and SEC/DIV (Seconds per division) knobs. A division refers to the distance between two
neighboring parallel dashed lines. The vertical divisions denote voltage and the horizontal divisions denote time. To
use the oscilloscope and follow these steps:
1. Disconnect the two banana leads from the DMM.
2. Connect the coaxial end of the BNC cable shown in Figure 1.15 to Channel 1 on the oscilloscope.
Figure 1.15: This is a BNC connector
3. Clip the oscilloscope probes black micrograbber to the black micrograbber from the power supply (ground).
Ground is a common node or connection shared by many different components, and is
considered to have a potential or voltage of zero. In this case, ground is the connection at
the black wires.
4. Connect the red micrograbber of the oscilloscope probe to the red micrograbber from the power supply. Turn
the power supply back on, and set the voltage to 0V.
5. Turn the oscilloscope on by pressing the white button on the top of the scope. Press the CH 1 button, to view
the measurements of the Channel 1 signal.
6. Set the oscilloscope VOLTS/DIV knob for 2V/DIV. The current VOLTS/DIV will be displayed in the bottom left
corner of the display. See Figure 1.16.
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Figure 1.16: These are the Channel 1 adjusting knobs
7. Slowly adjust the voltage knob on the power supply from 0V to 5V, and observe the oscilloscope.
What happens to the signal on the oscilloscope as the power supply is adjusted? If it does
not change, ask the TA to look at the scope.
8. Leave the power supply connected to the oscilloscope and move on to the next task in this section: ‘Software
Tools.’ Use Excel to graph the oscilloscope display as the power supply is being adjusted.
1.5
Software Tools
Two software applications will be used in ENGR201 labs: Open Choice and LTSPICE.
1.5.1
OpenChoice
Using the OpenChoice Desktop software, waveforms can be imported from the oscilloscope. These waveforms can
then be viewed in OpenChoice or imported to Microsoft Excel. This will be a valuable tool for creating visuals for
presentations and figures for reports.
Follow these instructions to capture data from an oscilloscope to a computer:
1. Using a female to female serial cable (as shown in Figure 1.17), connect the oscilloscope to the serial port on
the back of the computer and turn the oscilloscope on.
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Figure 1.17: This is an RS 232 female serial connector
2. Using a power supply, create some data to be captured.
3. Configure the oscilloscope to correctly view the waveform on CH1.
4. On the computer, open OpenChoice Desktop software by clicking: Start → All Programs → ECE Course
Programs → OpenChoice Desktop → OpenChoice Desktop. The program should look similar to Figure 1.18
Figure 1.18: This is the OpenChoice application
5. Click Select Instrument and select ASRL1::INSTR.
6. Capturing Screenshots: OpenChoice software can be used to capture a screenshot of the oscilloscope, as
shown in Figure 1.19. Click on the ‘Screen Capture’ tab, select ‘Instrument,’ and click ‘Get Screen.’ It takes
several minutes to download the screen, but it can be a useful tool for displaying waveforms in reports or
presentations.
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Figure 1.19: Screenshots can produce high quality presentation figures
1.5.2
LTspice
LTSpice is a design tool that allows for the design and simulation of circuits.
Today a simple resistor network will be created. In future labs it is required that all circuits used during the
experiment are created in LTSpice and included in the lab report. Use LTSpice to create the resistor network shown
in Figure 1.20.
In order to use the LTSpice tool, follow these steps:
1. Open LTSpice: Go to Start → Programs → LTSpice
Figure 1.20: The ’ground’ symbol in the lower left corner of should be attached by a wire as shown.
2. Add components: Go to the component library by clicking on Edit → Component.
Add a resistor: Enter the letter ’R’ and then click on the schematic to place the resistor. (Note that parts
can be rotated by pressing CTRL + R before placing them onto the schematic.)
Add a voltage source: Choose the part ’voltage’, and then click on the schematic to place the voltage
source.
Add a ground: Choose part ground (or press G), and then click to place.
3. Connect the parts: Select Edit → Draw Wire (or press F3).
Placing wires: Click on the end of a component, and then click on the other end of a component. A wire
will then connect the two selected ends.
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4. Set the values of components: Right click on the values and change them to the values shown in Figure 1.20.
5. Simulation: Click on Simulate → Run
In the transient tab, enter the collowing values and select ok:
Stop Time: 1
Start Time: 0
Max Time Step: 1
Click on a node to measure that voltage or on a component to measure current through that component.
6. View Netlist: Click on View → Spice Netlist
7. Finish: To import the image of the schematic into a Microsoft Word document click on Tools → Copy bitmap to
Clipboard then open a Word document and press Ctrl+V to paste the image.
1.6
Lab Report
Write a clear and concise report. Turn in the typed report next week.
The report should include the following:
1. Any data recorded during the lab.
2. All circuits built during lab (drawn using LTSPICE or a similar program), including a simulation and Netlist.
3. Use Ohm’s law and the recorded values for voltage and resistance to calculate current. Compare this value
with the value measured by the DMM.
4. If any modifications were made to a design, explain why such steps were taken and how it helped the end
result.
5. Explain how the lab relates to your discipline and where you might be able to use some of the information
learned in lab. (Be as specific as possible, citing real-life examples)
6. Any calculations performed in this lab.
7. Length is not a requirement, but completeness is. Don’t forget any important information.
Current guidelines and an example lab report are available on the lab website.
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