Oscilloscope II
-
Upload
leotakesleo -
Category
Documents
-
view
251 -
download
0
Transcript of Oscilloscope II
-
7/28/2019 Oscilloscope II
1/19
Oscilloscope II
PHYS-1008
Winter 2012
-
7/28/2019 Oscilloscope II
2/19
REMINDER
IMPORTANT!
When you record a number in your book,
dont forget the units.
If its a measurement dont forget the error.
Error on your instruments
Analog = Half of the smallest division
Digital = +/- 2 the last stable digit
-
7/28/2019 Oscilloscope II
3/19
Significant Figures(p. 24 in PHYS-1007 lab manual)
Results should have the same number of
decimal places as the error.
Calculations: 2 significant figures for the error.
Final result: 1 significant figure for the error.
-
7/28/2019 Oscilloscope II
4/19
The Oscilloscope
Measure the potential difference (i.e. Voltage)across a component as a function of time.
rence
Trigger
value
Po
tentialdif
f
(units
)
Time (units)
Falling (- slope) Rising (+ slope)
-
7/28/2019 Oscilloscope II
5/19
Function generatorType of signalFrequency Display
& Control
Frequency Range
AttenuatorAttenuator
V(t)
Rg= 50
to
oscilloscopeOutput casings =
common ground
-
7/28/2019 Oscilloscope II
6/19
OscilloscopeTime scale
(sweep time / div)
Trigger
Level (V), slope
(+/-)Intensity / Focus
Channel A and B
V(t)
Rg= 50
RS= 1M
CS= 21pF
-
7/28/2019 Oscilloscope II
7/19
Experiment Outline
Output Resistance of the Function Generator
Measuring the Capacitance of the Coaxial
Cable
e o e an a ower upp y(Converting AC to DC)
YOU WILL ONLY BE EXPECTED TO DO THELAST TWO EXPERIMENTS OF THE LAB.
-
7/28/2019 Oscilloscope II
8/19
Coaxial Cable + BNC connector
External Insulator
Ground
Conductive Mesh
Shield from E-M noise
Insulator
Internal Conductor
Carry the signal
-
7/28/2019 Oscilloscope II
9/19
Indicates how much time a capacitor can take to charge
or discharge.
-
7/28/2019 Oscilloscope II
10/19
2 Measuring the Capacitance of the
Coaxial Cable Assemble Circuit: connect BNC connector + Resistor combination into
the Function Generator.
Make note of colour code of the resistor.
BNC-Alligator coaxial cable: clip one end to resistor, clip other lead to
ground casing, attach BNC to oscilloscope.
Set the frequency on the generator to 800Hz and SQUARE wave. Set oscilloscope trigger to negative slope.
Adjust TIME/DIV control until one complete decay curve fills screen.
Choose a grid line for an arbitrary V=0 and to
= 0.
Measure Vo at to.
Proceed to measure V for four more points of t. Use the large divisions in
t to make things easier.
Plot ln(V) ln(t) vs. t and get RC from slope and thus Cc.
-
7/28/2019 Oscilloscope II
11/19
2 Measuring the Capacitance of the Coaxial Cable
Assemble Circuit: connect BNC connector +
Resistor combination into the Function Generator.
Make note of colour code of the resistor.
BNC-Alligator coaxial cable: clip one end to resistor,
clip other lead to ground casing, attach BNC tooscilloscope.
Set the frequency on the generator to 800Hz and
SQUARE wave.
V(to) = Vo
Set oscilloscope trigger to negative slope.
Adjust TIME/DIV control until one complete decay
curve fills screen.
Choose a grid line for an arbitrary V=0 and to = 0.
Measure Vo at to.
Proceed to measure V for four more points of t.
Use the large divisions in t to make things easier.
Plot ln(V) ln(t) vs. t and get RC from slope and
thus Cc.
V = 0
t = 0
-
7/28/2019 Oscilloscope II
12/19
AC/DCAC from Power
station, along
electrical lines and
substations to
your home...
... From the wall to
your devices AC
adaptor which
converts it to DC.
-
7/28/2019 Oscilloscope II
13/19
The Diode(solid state switch)
V
t
50 F
10 k
-
7/28/2019 Oscilloscope II
14/19
The Diode(solid state switch)
V
t
50 F
10 k
-
7/28/2019 Oscilloscope II
15/19
The Diode(solid state switch)
V
t
50 F
10 k
X
-
7/28/2019 Oscilloscope II
16/19
3 The Diode and a DC Power Supply Assemble the circuit as
shown
Set Function Generator to60Hz, SINE wave.
Set Oscilloscope to +
TO CHANNEL BTO
CHANNEL
s ope, sw c oDUAL, and SOURCE switchto INT.
Disconnect the capacitor.Turn ON oscilloscope butleave FG turned OFF: youshould see 2 horizontallines.
A
-
7/28/2019 Oscilloscope II
17/19
3 Effect of the Diode Turn on Function Generator and increase output voltage
until you have a SINE wave with 8V peak-to-peak.
CH. A SINE WAVE CH. B RECTIFIED SINE WAVE
Draw wave forms.
Superimpose both waves. In your discussion, commenton the relationship between both waves. Why doesnt
the rectified wave reach zero?
-
7/28/2019 Oscilloscope II
18/19
3 Effect of the Diode + Capacitor Connect the Capacitor.
Switch Channel B to ground, GND. Line up horizontal line
near bottom of screen. Switch to DC and measure VDC.
Draw waveforms.
Switch Channel B to AC.
Increase Volts/Div on Channel B to magnify the ripple.
Measure the amplitude of the ripple and calculate the
Quality of the DC supply.
In your Discussion comment on the quality of the signal
and the importance of the Capacitor in use with
everyday appliances (e.g. your laptop).
-
7/28/2019 Oscilloscope II
19/19
You can leave when you have:1) Taken four measurements of V(t).
2) Preliminary graph of ln(V) ln(Vo) vs t.3) Calculated RC and Cc.
5) Measured VDC and Ripple Amplitude, Vripple.
6) Calculated DC Quality, Q.
Dont forget to record the uncertainty of yourmeasurements and units!