intro to dmm

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Intro to the Mechatronics Lab Intro - 1

Introduction to the Mechatronic Engineering Laboratory Equipment

Learning Objectives: By the end of the lab, you should be able to:

• Properly use a triple-output power supply, digital multimeter, function generator, and

oscilloscope.

• Measure oltage and current using the digital multimeter and oscilloscope.

• !se a solderless breadboard to build an electronic circuit.

Pre-Lab Preparation: "atch the following #ou$ube ideos:

Breadboard %igital Multimeter &unction 'enerator (scilloscope

Components:

• )esistors: one each of: 1** Ω, + Ω, .1 Ω, 1* Ω, 1** Ω, 1 MΩ, and two 1 Ω resistors.

Introduction: ach worstation in the lab consists of the e/uipment shown in &igure 1.

Figure ! Laboratory e/uipment in the Mechatronic ngineering Laboratory. $he multimeter, arbitrary waeformgenerator and oscilloscope are connected to the computer ia 'P-IB.

$he purpose of each of these deices, briefly, is:

• $he "P E#$#%& '(IPLE O)'P)' PO*E( +)PPL, will be used to supply the %0 power

needed to operate your circuits.

• $he "P #%& .I/I'&L M)L'IME'E( often referred to as the %MM2 will be used to

measure resistance, oltage, and current.

• $he "P ##0%& F)1C'IO1 /E1E(&'O( will be used to proide arious types of time-

arying signals to your circuits.

• $he "P 2$%# O+CILLO+COPE often referred to as the 3scope2 will be used mainly to

display how circuit oltages ary with time.

• $he PE(+O1&L COMP)'E( may be used to program the microcontrollers that you will

learn about in later labs.

#ou will get to use each of these deices in this laboratory session. $his guideline contains the basicoperating instructions for the test and measurement e/uipment described aboe. It also includes a

number of e4ercises identified by a framed border on the page. $he e4ercises will help you learn

about the e/uipment and the types of measurements you can mae, so that you will be prepared for

the many interesting e4periments that you will perform this semester.

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5an 6os7 5tate !niersity %ept. of Mechanical and 8erospace ngineering re. 1.9.1 +68;+*1<

http://www.youtube.com/watch?v=f8XohYB1pRY

http://www.youtube.com/watch?v=fv36-Ahy06c

http://www.youtube.com/watch?v=_pDz6e2ADew

http://www.youtube.com/watch?v=5yNDSkQBEy0

http://www.youtube.com/watch?v=f8XohYB1pRY

http://www.youtube.com/watch?v=fv36-Ahy06c

http://www.youtube.com/watch?v=_pDz6e2ADew

http://www.youtube.com/watch?v=5yNDSkQBEy0



Intro to the Mechatronics Lab Intro - +

+tudy the operating instructions3 and per4orm each e5ercise 6hen it is presented! Ma7e any

ca8cu8ations at the time requested!

'he +o8der8ess 9readboard

$he circuit board we will use throughout the semester is shown in &igure +. 5ome common names

for these boards are solderless circuit boards, proto-boards, and more often2 breadboards!

0ircuit components = such as resistors, capacitors, op amps, transistors, etc. = simply plug into the

holes in the breadboard. ;o soldering is needed. &igure > shows how connections are made insidethe breadboard between the holes. .O 1O' insert anything 8arger than 00 &*/

CHANNEL

red line

red line

blue line

blue line

blue line

red line

CHANNEL

Figure 0! 5olderless breadboard -- $op ?iew. "ires and components can be simply inserted into the holes. .O

1O' insert anything 8arger than 00 &*/

CHANNEL

red line

red line

blue line

blue line

blue line

red line

CHANNEL

Figure #! Internal connections of the solderless breadboard -- $op ?iew. $he fifty holes in each of the two rows

between the red and blue lines are connected together internally. $he remaining holes are connected together in

groups of fie ertically.

;otice that the holes along the hori@ontal sets of red and blue lines are all connected along thelength of the lines. $hese hori@ontal strips are often called rails or 3bussesA, because they carry a

signal down the strip lie a bus carries people down a road. It is conentional to route power tothe strips near the red lines and ground to the strips near the blac lines. Follow this convention

when you build your circuits ;otice also how each set of fie holes aboe and below the

hori@ontal channels are connected together. $hus anything plugged into one of the set of fie

holes will be connected to anything else plugged into one of the remaining four holes of the set.

&igure < shows a circuit actually that for 4ercise >2 built on a breadboard. Power and common

ground are routed from the power supply to the solderless breadboard using red and blac test

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Intro to the Mechatronics Lab Intro - >

leads respectiely. $hese particular leads are called 3stacing banana-to-bananaA test leads. $he

socets they plug into at the power supply and on the breadboard are called 3binding postsA.Binding posts usually hae a captie screwable barrel that can clamp on a wire, which is either

wrapped around the internal metal post or poed into a transerse hole drilled through the post.

&igure < shows two short lengths of red and blac hooup wire that tae power and groundrespectiely from the binding posts on the breadboard to the power and ground busses on the

breadboard. $wo other short lengths of red and blac hooup wire ++-+< 8"' and stripped of

insulation C inch from each end2 tae power and ground respectiely from the busses at thecenter of the breadboard and route them down to the busses at the lower edge of the breadboard.Loo at the circuit schematic in 4ercise >, and see how the connections are made in &igure <.

Figure ! 0ircuit from 4ercise > built on a solderless breadboard. Power and ground are routed from the red and blac binding posts to the two busses at the center of the breadboard by two short lengths of red and blac hooup

wire ++-+< 8"' and stripped of insulation C inch from the end2. $wo other short lengths of red and blac

hooup wire tae power and ground respectiely from the busses at the center of the breadboard and route them

down to the busses at the lower edge of the breadboard.

Pay attention to the feel of the connection when you plug a lead into one of the holes of the

breadboard. $he socets for each hole inside the breadboard are made from a !-shaped metal

conductor. $hrough wear or by someone Damming too large a lead into one of the holes2, the !-channel can be bent open, which will result in a poor or intermittent electrical connection. $his is

one of the maDor disadantages of using a solderless breadboard and something to eep in mind

when you are troubleshooting a circuit that is behaing strangely. #ou should feel some frictionwhen you slide a lead into one of the holes, and oltage readings should be stable een if you

wiggle the leads slightly.

&ollow the conention of using red for power and blac or green2 for grounds when you wire Dumpers on your breadboard. $ry to also group and color-code other connections of the same type

to mae it easy to follow them around the breadboard. It is best to eep Dumpers and leads only as

long as needed shorter is usually better2 and neatly routed close to the breadboard. %oing so will')8$L# help when you hae to troubleshoot your circuit.

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Intro to the Mechatronics Lab Intro - <

'"E "P E#$#%& '(IPLE O)'P)' PO*E( +)PPL,

Outputs on Front Pane8

$his %0 power supply proides three separate outputs: a ariable * to E+* ? output rated at *. 8,

a ariable * to -+* ? output rated at *. 8, and a ariable * to EF ? output rated at +. 8. 8ll three

outputs share a single common 0(M2 connection. $he 0(M is the low side negatie2 for the E+*and EF ? output and the high side for the -+* ? output. 5ee &igure for the front panel.

Figure 2! %0 power supply. $his is a triple-output power supply, which means it has three, independent outputs: *

to F ?, * to E+* ?, and * to -+* ?. $he oltages for these outputs are referenced to 0(M also called 3commonA2

ground. $he terminal with the upside-down $ symbol is earth ground, which we will not use.

$his common connection is referred to as common ground. It is the point from which the output

oltages supplied by the ;$, ;0%, and -0% terminals, are referenced. $he 0(M output is to beconnected to circuit ground, i.e., the ground symbols in the schematics for the e4periments.

$here is also an e/uipment ground proided. $his is the terminal mared with the upside-down $-

shaped symbol. 8s a safety feature, each piece of e/uipment in the lab is connected to earth through

its >-wire power cord. If for some reason a short circuit occurred to the case of the instrument, theground wire would carry the short-circuit current to the earth, instead of you &or this reason, the

e/uipment ground is more commonly referred to as earth ground. "e will rarely use the %0 supplye/uipment ground.

<o8tage and Current .isp8ays

$he three push-button meter switches allow you to select one of the three outputs for display. $heoltmeter and ammeter always monitor the selected supply.

<o8tage &djust

$he EF? control nob sets the * to EF? output oltage.

$he±

+*? control sets the * to E+*? and the * to -+*? outputs simultaneously. "ith the $racing

)atio control nob turned fully clocwise to its Gfi4edH position, the oltage of the negatie supplytracs the positie supply within 1, giing balanced positie and negatie supplies.

$urning the $racing )atio control nob counter-clocwise out of its fi4ed position allows you to set

the oltage of the -+*? supply to a fi4ed fraction less than unity2 of the E+*? supply. &or e4ample,

you can set the -+*? supply to 1J> of the E+*? leel, but not to > times the E+*? leel. (nce this

ratio is set, the±

+*? control still controls both outputs and maintains a constant ratio between their

oltages.

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Intro to the Mechatronics Lab Intro -

1ote: 9e4ore hoo7ing up any circuit to the Po6er +upp8y3 you shou8d ma7e sure that the

vo8tage is set to 6hat you 6ant to avoid any overpo6ering o4 your circuit!

E5ercise ! -- .C +upp8y

• $urn on the power supply by pressing the white button labeled LI;. $he red L% display will

show the oltage output and current drawn for the output selected by one of the three GmeterH

pushbuttons.

• $urn the $racing )atio control to its Gfi4edH position. Press the E+*? meter button to displaythe E+*? output2 and adDust the ±+*? control nob to set the positie supply to E1?. Press the

-+*? meter button. $he oltmeter should read -1?. $he positie and negatie supplies are

balanced ±

1?2.

• 8dDust the $racing )atio control until the negatie supply reads -?. $he positie supply should

read E1 ?. 0hec that it does. #ou now hae a tracing ratio of #: E1? and -?2.

• $o see how tracing wors, press the E+*? meter button and readDust the±

+* ? control nob to

set the positie supply to E1K?.

• &inally, press the -+*? meter button. $he negatie supply should read -F?, since the oltage ratio

of #: was not changed.• *hy might this trac7ing ratio be use4u8=

>1ote: In addition to describing in your 8ab report 6hat you did in the E5ercises and 6hat

resu8ted during the 8ab session3 a8so 6eave into your narrative the ans6ers to the questions in

bo8d4ace type!?

Over8oad Indicators

8n oerload L% located ne4t to the ammeter will light when the %0 supply output is connected to a

load circuit2 that causes its current limit to be e4ceeded *.8 for the±

+*? supplies, +.8 for the

EF? supply2. $he cause of the oerload is usually a short-circuit. If you see an oerload light, turn

the power off immediately and double-chec that your circuit is wired correctly.

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Intro to the Mechatronics Lab Intro - F

'"E "P #%& .I/I'&L M)L'IME'E(

$he digital multimeter, or %MM as it is commonly called, is used to measure resistance, 80 and %0oltage, 80 and %0 current, continuity, and fre/uency. "e will not use most of the menu drien

features offered those we do need will be discussed at a later time.

'he Front Pane8

8s shown in &igure F, the front panel has two rows of eys to select arious functions. Most eys

hae a shifted function printed in blue aboe the ey. $o perform a shifted function, press the blue+hi4t ey the shift annunciator on the display will turn on2. $hen, press the ey that has the desired

label aboe it.

Power

Off

On

dBm

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Math

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Figure $! %igital Multimeter %MM2. $he %MM is used to measure resistance, oltage, and current.

(&1/E @ .I/I' Aeys

#ou can let the multimeter automatically select the range using autoranging, or you can select a fi4edrange using manual ranging. 8utoranging is default. $o select a higher less sensitie2 range, press the

∧ ey. $o select a lower more sensitie2 range, press the ∨ ey. If the input signal is greater than the present range can measure, the multimeter will gie an oerload indication G(?L%H2.

#ou can set the display resolution to 31 A, 321A, or 3$1A digits to optimi@e either measurement speed or

noise reDection. $he leftmost digit on the display is referred to as the G1G digit, since it can only be a

G*H or G1.H $he resolution is set to 31A digits at power-on. #ou can also ary the number of digits

displayed using the B and arrow eys.

#ou can select ranging and resolution for each function independently. $he multimeter remembers

the range and resolution when you switch between functions but not after you power off.

$he ne4t few paragraphs define general procedures for measuring resistance, oltage, current, and

fre/uency or period2, which you will use in subse/uent e4ercises. &amiliari@e yourself with the

procedures before attempting to mae the measurements described in the 4ercise + later on.

"o6 'o Measure (esistance

a. %isconnect any power in the circuit to be measured. b. 0onnect leads banana to mini-clip style2 to the "I and LO terminals mared %%% < Ma5

see &igure 2. It is best to measure resistance before placing a resistor or component in a

circuit otherwise, you may be measuring the resistance of some parallel combination of

elements2.

c. 5elect Ω 0* two-wire resistance measurement2.

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Intro to the Mechatronics Lab Intro -

d. Leae the meter on autoranging or select manual ranges of 1**Ω, 1 Ω, 1* Ω, 1** Ω, 1

MΩ, 1* MΩ, or 1** MΩ. Manual range allows you to choose the range of the measurement,

which might be helpful in certain situations.

1ote: (esistor va8ues are not e5act! 'hey have a to8erance on their nomina8 va8ue3 such as

D3 2D3 etc! *hen you measure their va8ue3 doub8e-chec7 that it is 6ithin the

speci4ied to8erance3 6hich can be deciphered by reading the associated co8or band

on the resistor!

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Rear

HI

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2+++'Ma.

3ARMS

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I

un-nown

re1i1tor

Figure ! )esistance measurement two-wire2. $he probe leads are connected to the rightmost I and L( terminals

on the %MM.

"o6 'o Measure <o8tage

a. 0onnect leads to the "I and LO terminals mared %%% < Ma5 see &igure K2.

?oltmeters are connected in parallel with the element. "e do not need to modify thecircuit when maing oltage measurements. 5ince oltages are measured GacrossH an

element, we simply place the leads on two points across the circuit element to be tested.

b. 5elect .C < or &C <. In the 80 olts function, the meter remoes the %0 component

and measures the )M5 alue of the 80 component, only.

c. Leae the meter on autoranging or select manual ranges of 1** m?, 1 ?, 1** ?, or 1***? * ? 802.

$++',-Ma.

(erminal1

ront

Rear

HI

!++'Ma.

2+++'Ma.

3ARMS

LO

HI

LO

u1ed onRear Panel

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Ratio Ref

I

4

5

Figure ! ?oltage measurement with the %MM. ;ote the location of where the leads attach to the %MM.

"o6 'o Measure Current

a. 8s shown in &igure 9, use the "I and LO terminals mared # & (M+. 8mmeters must be

connected in series with the element so that the current flowing GthroughH the element will

also flow through the ammeter. $herefore, it is necessary to brea7 the circuit and

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Intro to the Mechatronics Lab Intro - K

connect the ammeter in series at the brea7! Note the lead polarity with respect to the

current direction.

b. 5elect .C I or &C I using the shift ey2. In the 80 current function, the meter remoes

the %0 component and measures the )M5 alue of the 80 component, only.

c. Leae the meter on autoranging or select manual ranges of 1* m8 %0 only2, 1** m8%0 only2, 1 8, or > 8.

d. ;ote that current must go through the meter in order to complete the electrical circuit.

$++',-Ma.

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Rear

HI

!++'Ma.

2+++'Ma.

3ARMS

LO

HI

LO

u1ed onRear Panel

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Ratio Ref

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4

5

I R

Figure G! 0urrent measurement using the %MM. ;ote where the probes connect to the %MM it is different than foroltage measurement2. ;ote that to mae a current measurement, you must 3breaA the circuit in the branch where the

current flows and route it through the %MM. $hrough which terminal does current flow into the %MMN

"o6 'o Measure Frequency >or Period?

!se the "I and LO terminals mared %%% < Ma5 as you would for oltage measurements --

&igure K2. $he meter can measure fre/uency from > @ to >** @ period from *.>> sec to >.>

µsec2. &or fre/uency and period measurements, ranging applies to the signalOs input voltage, not

its fre/uency.

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E5ercise 0! -- (esistance measurements

Measure and record the actual resistance of each of the eight resistors listed on page 1:

1** Ω, + Ω, .1 Ω, 1* Ω, 1** Ω, and 1 MΩ. )efer to the procedure, Gow to Measure

)esistanceH aboe. 8lso record the color bands for each of the resistors. 5ince the resistorsused in this lab hae tolerance, their measured alue will be slightly different from their

nominal alue. &or e4ample, the 1** Ω resistor should measure somewhere between 9 Ω and1* Ω. 8lso note that the two 1 Ω resistors will not hae identical measured alues.

0alculate the actual tolerance of each resistor using the formula:

tolerancemeasured nominal

nominalx100=

-%

E5ercise #! -- <o8tage Measurements

"ire the circuit in &igure 1* see &igure 11 for wiring e4ample2. "ith your %MM

connected as a oltmeter, measure the oltage drop across each resistor, and measure ?5.!sing actual resistances, show oltage diision calculations to erify each of these measuredalues is reasonable.

!se the and > buttons on the %MM to change the resolution of your measurements.

*hen you go bac7 to t6o-decima8 reso8ution3 did the disp8ay round or truncate to obtain

the disp8ayed va8ue=

R R

RR

2

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3

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6

4

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4

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= 10 k

= 2 k

= 1 k

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1

2

3

4

R

R

R

Ω

Ω

Ω

Ω

= 10 Vdcs

V

) 1 1* Q

) + + Q

) > 1 Q) < .1 Q

?5 1* ?%0

Figure %: Circuit .iagram

Figure : *iring E5amp8e

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Bindin&,o1t1



Intro to the Mechatronics Lab Intro - 1*

E5ercise ! -- Current Measurements

"ith your %MM connected as an ammeter current2, measure and record I+, I& and I9 in

&igure 1*. !se (hmAs Law to Dustify the alue of I+ remember I+ ?5J) total2. !se current

diision to Dustify the alues of I& and I9.

Put this circuit aside! It 6i88 be used 8ater in the 8ab!

'"E "P ##0%&F)1C'IO1 /E1E(&'O( @ &(9I'(&(, *&<EFO(M /E1E(&'O(

$he function generator can output fie standard waeforms including sine, s/uare, triangle,

ramp, and noise. ach of these waeforms has @ero aerage alue, which means they aresymmetrical aboe and below the * ? reference line. #ou can also select one of fie predefined

arbitrary waeforms or download your own custom waeforms. #ou can internally modulate any

of the standard waeforms including arbitrary2 using 8M, &M, &5R, or burst modulation.Linear or logarithmic fre/uency sweeping is aailable for any of the standard waeforms e4cept

noise2 and arbitrary waeforms. &igure 1+ shows the front panel of the function generator.

In the M 1*F lab, we will only be interested in the standard and arbitrary waeforms. We will

not use the modulation capability of the generator.

&t po6er-on3 the 4unction generator outputs a sine 6ave at 7"H 6ith an amp8itude o4 %%

m< pea7-to-pea7 and a .C o44set o4 % < >into a 2%Ω termination?!

Power

Off

On

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Figure 0! &ront panel of the P >>1+*8 function generator

'he Front Pane8

$he front panel has two rows of eys to select arious functions and operations. 6ust lie the

%MM, most eys hae a shifted function printed in blue aboe the ey. $o perform a shifted

function, press the blue +hi4t ey the 5hift annunciator on the display will turn on2. $hen, press

the ey that has the desired label aboe it. If you accidentally press +hi4t, Dust press it again toturn off the 5hift annunciator.

Front-Pane8 1umber Entry

#ou can enter numbers for different alues to change fre/uency, amplitude, %0 offset, etc.2from the front panel using one of three methods.

1. nter desired numeric alue using Gnter ;umberH mode.

Most eys also hae a number printed in green ne4t to the ey. $o enable the number mode,

press the Enter 1umber ey the ;um annunciator on the display will turn on2. $hen, press

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the eys that hae the desired numbers printed ne4t to them. &or e4ample, to select the

number G1*H, press Enter 1umber, then press the ey with the ne4t to it, then press theey with the % ne4t to it, then press the Enter button aboe the 5hift ey2 to commit the

alue you entered.

If you accidentally press Enter 1umber, Dust press +hi4t, then press Cance8 to turn off the

;um annunciator.

If the number re/uires units, press the appropriate arro6 ey. If the number does not re/uireunits, press the Enter ey.

+. If one of the displayed numbers is flashing you can use the arrow eys to edit the flashing

digit.

∧ Increments the flashing digit.

∨ %ecrements the flashing digit.

> 0auses the ne4t digit to the right to flash.

0auses the ne4t digit to the left to flash.

In this case, you are merely changing the alue of the displayed number, and you do not need

to enter the units.>. #ou can also change the alue of the flashing digit by turning the nob.

$urning the nob clocwise will increment the flashing digit. It will also cause digits to the

left of the flashing digit to change if the nob is turned far enough.2 $urning the nob counter clocwise will decrement the flashing digit. It will also cause digits to the right of the

flashing digit to change if the nob is turned far enough.2 #ou can also use the nob along

with the leftJright arrow eys to modify the displayed number.

'he Front-Pane8 Menu

$he front-panel menu offers access to many more features and capabilities of this generator. Most

of these features will not concern us in the M 1*F Lab. (nly one of these features is of interestat this time. $hat feature is output termination.

Output 'ermination

$he function generator has a 2% Ω output impedance on the O)'P)' terminal. #ou can specify

whether the load you are connecting is a 2% Ω load or an open circuit "I/" 2. $hose are the

only two choices.2

$o select the output termination1. Press the +hi4t 7ey and then the Menu On@O44 ey to turn on the menu.

+. Press the ey three times to moe across to the .: +,+ ME1) choice.

>. Press the ∨ ey to get to the O)' 'E(M command.<. Press the ∨ ey a second time to get the place where you can change the e4pected output

impedance alue either 2% Ω or "I/" 2. ;ote that the default alue is 2% Ω, which is

also the alue selected when the function generator is first powered on. &or ALL the

measurements you will do in M 1*F, you should select "I/" .

. !se the B and eys to select between the 2% Ω and "I/" choices.

F. Press Enter. $his saes the change and turns off the menu.

'he section on mismatched 8oads be8o6 discusses 6hat happens 6hen you do not terminate

into a 2% Ω 8oad or an open circuit!

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Intro to the Mechatronics Lab Intro - 1+

'"E "P 2$%# O+CILLO+COPE

$he front panel of the oscilloscope the portion to the right of the display2 has nobs, grey eys,and white eys. $he nobs are used most often. $he white eys are instant action eys and menus

are not associated with them. $he grey eys bring up softey menus at the bottom of the display

that allow you access to many of the oscilloscope features.

$he softeys which are also grey2 are located below the display. 8 softey is a push-buttonswitch that allows you to select from seeral possible functions. ach possible selection is

displayed in se/uence by repeatedly depressing the softey. Leae the desired function isible on

the display.

$he status line, located at the top of the display, lets you /uicly determine the setup of theoscilloscope.

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Dela=ed

Dela=

E.ternal (ri&&er

Soure

Mode

('

Slo,e

Cou,lin&

Le7el

Holdoff

IO

2 ! '

Line

+@++1 $++ 1 2 R*N

2 ! E.t Line

-

2

Print

*tilit=

Figure #! $he oscilloscope. $his deice is used to measure dynamic signals, i.e., signals that change relatiely

/uicly.

Probe1 Attention!

(scilloscope leads are called probes. $he low side of the probe the alligator clip2 is usually tied

to the scope case, which is connected to earth ground through its >-wire power cord.

If you hae connected the e/uipment ground from any other piece of e/uipment i.e. the power

supply2 to your circuit, then the low side of the probe must be connected to the same point in the

circuit as the e/uipment ground.

Most of the circuits built in this lab, howeer, will hae a common ground as discussed in the$riple (utput Power 5upply section earlier. "hen using common ground, the alligator clip can be

connected anywhere in the circuit. $he only restriction in this case is that if you use two probes,

both alligator clips M!5$ be connected to the 58M point in the circuit.

Probes are labeled with their attenuation factor = either 1**S, 1*S or 1S. 8 1*S probe reducesthe amplitude of the input signal to 1J1*th of its actual alue. 8 1**S probe reduces the amplitude

of the input signal to 1J1**th of its actual alue. 8 1S probe does not attenuate the signal.

$o set the probe attenuation factor for the probe connected to channel 1:

1. Press the ey it is a grey front-panel ey2.

©




Intro to the Mechatronics Lab Intro - 1>

+. ;e4t, toggle the Probe softey to change the attenuation factor to 1* since we hae

1*S probes in this lab2.

$o set the probe attenuation factor for the probe connected to channel +:

1. Press the 0 ey, then toggle the Probe softey to set the correct attenuation factor.

1ote: i4 you do not correct8y set the attenuation 4actor in the osci88oscope3 the osci88oscope

may on8y disp8ay @%th

o4 the actua8 reading!

E5ercises

&or e4ercises through 11, you will be connecting the function generator directly to the

oscilloscope. 5ince the oscilloscope has a ery high input impedance appro4imately 1 MΩ by

itself and 1* MΩ with a 1*4 probe2, you will need to set the output termination of your

function generator to "I/" to match the impedance of the scope see page 92.

8fter setting the I' T termination, set the function generator to output an K ? pea-to-pea** @ triangular wae with an offset of + ?%0. $o do this:

1. 5elect the triangular waeshape.

+. $o set the output fre/uency to ** @:a. Press the Freq ey to enable the frequency modify mode.

b. Press the Enter 1umber ey to enable the number mode. ;otice that the ;um

annunciator turns on and G;$) ;!MH flashes on the display.

c. Press 2, then press % twice.d. Press to set the units to @.

>. $o set the output amplitude to K ?P-P:a. Press the &mp8 ey to enable the amplitude modify mode. b. Press the Enter 1umber ey to enable the number mode.

c. Press .

d. Press the ∧ to set the units to ?P-P.

;ote that if you had wanted an amplitude of 1* m?P-P you would

need to press +hi4t before pressing ∧ since m is in blue.

<. $o set the offset to + ?%0:

a. Press the O44set ey to enable the offset modify mode.

b. Press the Enter 1umber ey to enable the number mode.

c. Press 0.d. Press Enter. 5ince it is understood that the offset oltage is a %0 oltage, no units are

needed. $he display will read ?%0. ;ote also that once you hae set an offset oltage,

the word GoffsetH is displayed een if you go bac and display the amplitude orfre/uency again2.

E5ercise 2! -- .isp8aying a signa8 automatica88y!

a. 0onnect the output of the function generator to the input channel 1 of the oscilloscope as

shown in &igure 1<.

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Intro to the Mechatronics Lab Intro - 1<

Ma.#!'

S>NC

)ENERA(OR*NC(ION

O*(P*(

bla- li,

red li,

alli&ator li,

,robe

2

OSCILLOSCOPE

!>

Figure ! 0onnecting the function generator to the oscilloscope

b. Press the &utosca8e ey a white front-panel ey2. $he oscilloscope

automatically changes the front-panel setup to display the signal.

;otice that the 80 signal is centered ertically on the oscilloscope screen. ;otice, also, that the

ground * ?2 reference symbol at the right side of the screen is one diision down from thecenter of the screen.

0hec the status line at the top of the screen. #ou should see the following:

a. 8t the left side, there should be a number to indicate that channel 1 is on. $he isfollowed by the ertical scale sensitiity for channel 1 in olts per diision + ? in

this case2.

b. If no signals are connected to channel + or to the e4ternal Dac, then the ne4t thingyou will see in the status line will be an arro6 followed by %!%%s to indicate that the

time reference is located at the center of the screen.

c. $he ne4t item in the status line will be the time scale sensitiity in seconds per

diision ** µs in this case2.

d. ;e4t, there should be an up-arro6 and the number . $his tells us the scope istrigging on the positie slope of the signal applied to channel 1. 8 down-arrowindicates that the scope is triggering on the negatie slope.2

e. $he last item in the status line is the word ()1, which tells us that the scope is

continually ac/uiring data and displaying the most recent trace.

9e4ore each o4 the ne5t si5 e5ercises3 press the &uto-sca8e 7ey so that the discussion matches

6hat you see!

E5ercise $! /etting 4ami8iar 6ith the vertica8 >vo8tage? contro8s!

a. $he Position nob moes the signal ertically, and it is calibrated. 8s you turn the Position

nob, notice that the ground symbol on the right side of the display moes in conDunctionwith the Position nob. 8lso, notice that as you turn the Position nob, a oltage alue isdisplayed for a short time indicating how far the ground reference is located from the center

of the screen. "hen the ground reference moes off screen, the ground symbol changes to an

arrow and points in the direction up or down2 to gie you some idea of where the ground

reference is.

b. 0hange the ertical sensitiity with the <[email protected] nob. ;otice that it causes the status line to

change, and also changes the si@e ertically2 of the displayed waeform.

c. Press the ey, and a softey menu appears. $oggle each of the softeys and notice which

©





eys cause the status line to change. ;otice, also, which softeys cause a change in the

display andJor the position of the ground reference. ;otice that when you change the input

coup8ing from %0 to 80, the signal moes ertically so that it is symmetrical aboe and below the reference line. $his means that the %0 component has been remoed.

d. 0hannels 1 and + hae a vernier softey that allows the <[email protected] nob to change the ertical

step si@e in smaller increments. $hese smaller increments are calibrated, which results in

accurate measurements een with the ernier turned on.e. $o turn the channel off, either press the ey a second time or press the left-most softey.

E5ercise ! -- +ome o4 the horiHonta8 >time base? contro8s

a. $urn the '[email protected] nob. ;otice the change it maes to the status line and to the displayed

waeform. $he '[email protected] nob changes the sweep speed form + ns to s in a 1-+- stepse/uence, and the alue is displayed in the status line.

b. Pressing the [email protected] ey brings up a softey menu with si4 softey choices. "e will

not discuss their functions at this time. ;or will we discuss the %elay nob.

E5ercise ! -- +ome o4 the trigger contro8s!

a. $urn the trigger Leve8 nob and notice the changes it maes to the display. In particular,

notice that the waeform moes hori@ontally as the leel changes. 8lso, notice that a oltage

alue is displayed since, the trigger leel is a oltage leel2. "hat happens if you moe thetrigger leel aboe or below the displayed waeformN $ry this for channel 1 input coupling set

to 80 and for channel 1 input coupling set to %0.

b. Pressing the +ource ey brings up a softey menu. $oggle each of the softeys and notice that

each ey causes the status line to change. ;otice, also, what happens to the displayedwaeform. )eset the source to before going on to part c. "e will not discuss these menus at

this time

E5ercise G! -- Ma7ing 4requency measurements automatica88y!

a. Press the 'ime ey.

b. $oggle the +ource softey to select a channel for the fre/uency measurement channel 1 in

this case2.

c. Press the Freq softey. $he oscilloscope automatically measures the fre/uency and displays

the result on the lower line of the display. $he number in parentheses after the word G&re/H isthe number of the channel that the oscilloscope used for the measurement. $he oscilloscope

retains in memory and displays the three most current measurement results. If you mae a

fourth measurement, the left-most result is dropped. $ry pressing other $ime measurementsofteys to obsere their behaior.

E5ercise %! -- Ma7ing vo8tage measurements automatica88y!

#ou can measure the following oltage parameters automatically with the oscilloscope: pea-to-

pea, aerage, )M5, ma4imum, minimum, top, and base. &igure 1 and &igure 1F, below, show pulses with some of the oltage measurement points labeled.

©




Intro to the Mechatronics Lab Intro - 1F

'to,

'ma.

'min

'ba1e

Figure 2: Pulse where top and bottom are well-defined.

'ma. 'to,

'min 'ba1e

Figure $! Pulse where top and bottom are not well-defined.

'o ma7e vo8tage measurements automatica88y:

a. Press the <o8tage ey.

$he +ource softey selects a channel for the oltage measurement.

$he ?oltage Measurement softeys gie you the choice of <P-P, <&</, and <(M+.

$he C8ear Meas softey erases any measurement results from the display, and remoes the

hori@ontal and ertical cursors from the display.

$he 1e5t Menu softey replaces the current softey menu with si4 additional softey

choices.

b. Press <P-P and <&</.

$hese alues should correspond to the oltages set on the function generator. )emember,

offset oltage and aerage oltage are the same thing.2

c. Press the <(M+ softey. $he oscilloscope automatically measures the (M+ oltage of this %0coupled signal and displays the result. ;e4t, change the input coupling to 80 and try this

measurement again. ;ote that the (M+ alue is smaller. $his is because the %0 component

has been bloced from the Oscope. )emember that the total (M+ oltage is:

?)M5

P ? ACRMS

2+ E ?%0

2+

*hat va8ues do you measure= +et the input coup8ing bac7 to .C be4ore you begin step d!

d. Press the 1e5t Menu softey.

$he +ho6 Meas softey displays the hori@ontal and ertical cursors that show where the

measurement was taen on the signal.

$he ?oltage Measurement softeys gie you the choice of <M&J, <MI1, <'OP, and <9&+E.

$he Previous Menu softey return to the preious softey menu.

e. Press <M&J, press <MI1, then press +ho6 Meas.

©





E5ercise ! -- Changing output termination!

a. )efer to the section on (utput $ermination for the function generator, and set the output

termination to 2% Ω.

b. Measure, again, <P-P and <&</. $hese alues should now be twice the oltage alues

displayed on the function generator. By setting the output termination to * Ω, you hae told

the generator to e4pect to see a * Ω load and therefore change the displayed alue to bewhat you would e4pect if the generator were driing a * Ω load. Instead, it sees a load of 1*

MΩ. $he ne4t section on mismatched loads will e4plain this discrepancy.

MI+M&'C"E. LO&.+

Kuestion: What happens when the source and load impedances do not match?

&ns6er: 'he vo8tage app8ied to the 8oad 6i88 not match the vo8tage va8ue disp8ayed on

the 4unction generator >be it amp8itude or o44set vo8tage?!

)ecall from the section on (utput $ermination that the function generator allows you to choose

an output termination of either * Ω or I' T. In e4ercises through 1*, we chose the I' Toutput termination, because the input impedance of the oscilloscope with a 1*4 probe is

appro4imately 1* MΩ practically an open circuit2. In e4ercise 11, we chose the * Ω output

termination and found a large discrepancy between the oltage displayed on the functiongenerator and the oltage supplied to the Oscope.

$he function generator can be modeled see &igure 12 as an ideal oltage source, ?';, in

series with the generatorOs * Ω output impedance. $o simplify the discussion, we will assume

this impedance is purely resistie and label it as ) ';.

V

R

#en

#en

$%&C'()& *+&+R')R

-

-

= 50 Ω

Figure ! 8 model representation of the function generator.

'he 4unction generator is designed so that the vo8tage you set on the disp8ay is equa8 to</E1 i4 "I/" is chosen3 or is one-ha84 </E1 i4 2% Ω is chosen!

8 passie load can be modeled as an impedance. 8gain, for simplicity, we will assume this load

is purely resistie and label it as ) L(8%. 8s &igure 1K shows, the load is connected in series with

the generator impedance. $herefore, the oltage supplied to the load, ?5, is by oltage diision2

some fraction of ?';.

©




Intro to the Mechatronics Lab Intro - 1K

V

R

#en

#en

$%&C'()& *+&+R')R

-

-

= 50 Ω

Vs R load

Figure ! &unction generator with load.

?5

) L(8%

) '.;

E ) L(8%

?'.;

In e4ercises through 1*, we selected I' T termination, and our load the oscilloscope2 was

1* MΩ. $he oltage set on the function generator display was K ?P-P plus + ?%0 offset. $he

oltage supplied to our load was

?5

1*M

* E 1*MK?

P-P E

1*M

* E1*M+?

%0 ≅ K?

P-P E +?

%0

$he oltage supplied matched the oltage displayed on the function generator.

In e4ercise 11, we chose an output termination of * Ω. "hen this was done, the function

generator changed the displayed oltage alue ;($ the actual oltage it output2 to be < ?P-P

with a 1 ?%0 offset. $he actual signal output did not change from K ?P-P with a + ?%0 offset. #oucan see this on the 3scope by going through the steps of changing the output termination and

watching the 3scope trace. $he oltage alues displayed by the function generator are haled, but

there is no change in the oltage that the 3scope measures2

If we actually had a * Ω load instead of the 3scopeAs 1* MΩ), and * Ω output termination

were selected on the function generator, then the oltage displayed on the generator would matchthe actual oltage being supplied to the load.

"hen connecting the function generator to a circuit, the impedance the function generator sees is

usually much smaller than 1* MΩ, and is also usually much larger than * Ω. $herefore, 6e 6i88

usua88y see a discrepancy bet6een the vo8tage supp8ied to the 8oad and the vo8tage disp8ayed

on the 4unction generator! Reep this in mind

&or e4ample, if a circuit has an impedance of +* Ω and you set the function generator to ?

either amplitude or offset2, then from &igure 19, the oltage supplied to the load will be

V V V M

M V S 1:.<-

+-*-*

+-*-

1*JJ+-*-*

1*JJ+-*=

Ω+Ω

Ω≈

ΩΩ+Ω

ΩΩ=

;ote that +*Ω..1*MΩ means +*Ω in parallel with 1*MΩ2.

If I' T is selected, the function generator will display ?. If *Ω termination is selected, then

the function generator will display +.?.

©





5ince there will usually be a discrepancy between the oltage displayed on the generator and the

oltage supplied to the load, it is best to set the oltage to the desired alue by placing the Oscopein parallel with the load and measuring the oltage supplied. 5ee &igure 19.2

V

R

#en

#en

$%&C'()& *+&+R')R

-

-

= 50 Ω

Vs

Rckt

R/scoe

= 250Ω = 10Ω

)D = Rckt

R/scoe

Figure G! 0ircuit schematic showing Oscope used to measure supply oltage. $he input impedance of the 3scope by

itself is about 1 MU and about 1* MU with a 1*4 probe.

"ith the 3scope placed in parallel to the circuit, the total load the generator sees is the parallel

combination of ) 0R$ and ) L(8%, or +<9.9 Ω. 5ince the 3scope impedance is so high, it iseffectiely an open circuit and has little effect on the oltage being supplied to the circuit.

E5ercise 0! -- &C Measurements

$he circuit used in 4ercise > is shown again in &igure +*. $his time, you will use your function

generator to supply a ? pea-to-pea sinusoid with + ?%0 offset.

5et this oltage using your oscilloscope to measure the pea-to-pea alue and the aerage

alue. )ecord the alues measured with your oscilloscope and the alues displayed on your

function generator. 5tate whether you hae selected I' T or * Ω termination of your

function generator.

R R

RR

2

!

3

#

4

'2

6

4

'!

6

4

'3

6

4

'#

6

4

6'

1

I1

Ib

Ia

R

= 10 k

= 2 k

= 1 k

= 5.1 k

1

2

3

4

R

R

R

Ω

Ω

Ω

Ω

sV = 5V- 2Vdcsinusoid

Figure 0%! 0ircuit from 4ercise >

Measure and record the oltage drop across each resistor using both your 3scope and your %MM."ith the 3scope, you will measure ?P-P, ?)M5, and ?8?'. "ith the %MM, your will measure 80

?)M5 and %0 ?.

©


and 1*4 probe

and 1*4 probe



Intro to the Mechatronics Lab Intro - +*

"ith your %MM connected as an ammeter, measure and record each current indicated in &igure+*. #ou will need to measure both 80 I)M5 and %0 I. 0urrent cannot be measured with the

oscilloscope with the probes that we hae. $here are special 3scope probes called, Gcurrent

probesH that can be used to mae current measurements with a 3scope.

Documents

intro to dmm