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UNIVERSITY OF CALIFORNIA
College of Engineering Department of Electrical Engineering and Computer Sciences
EECS 145L: Electronic Transducer Laboratory
FINAL EXAMINATION December 13, 1994 5:00 - 8:00 PM
You have three hours to work on the exam, which is to be taken closed book. Calculators are OK, but not needed. Total points = 200 out of 1000 for the course.
1 ______________ (30 max) 2 ______________ (32 max) 3 ______________ (30 max)
4 ______________ (50 max) 5 ______________ (34 max) 6 ______________ (24 max)
TOTAL _____________ (200 max)
COURSE GRADE SUMMARY
LAB REPORTS:
4 __________ 5 __________ 6 __________ 7 __________ 11 __________
12 __________ 13 __________ 14 __________ 15 __________ 16 __________
17 __________ 18 __________ 19 __________ 25 __________
LAB TOTAL =_______ (500 max)
LAB TOTAL
LAB PARTICIPATION
MID-TERM #
MID-TERM #
FINAL EXAM
TOTAL COURSE GRADE
____________
____________
____________
____________
____________
____________
(500 max)
(100 max)
(100 max)
(100 max)
(200 max)
(1000 max)
COURSE LETTER
GRADE
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Problem 1 (30 points)
Give definitions (20 words or less) for the following terms:
1.1 (5 points) Accuracy of a sensor
1.2 (5 points) Precision of a sensor
1.3 (5 points) Seebeck emf
1.4 (5 points) Angle sensor (resistor)
1.5 (5 points) PIN photodiode
1.6 (5 points) Photovoltaic mode of a photodiode
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2.5 (4 points) Name two different sensors for measuring light
2.6 (4 points) Name two different actuators for producing light
2.7 (4 points) Name two different sensors for measuring force
2.8 (4 points) Name two different actuators for producing force
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Problem 3 (30 points)
3.1 (10 points) Describe how you would measure temperature over the range from 0°C to 600 °C with a precision of 0.2 °C and an accuracy of 0.5 °C
3.2 (10 points) Describe how you would measure temperature over the range from 0°C to 100 °C with a precision of 0.05 °C and an accuracy of 0.1 °C
3.3 (10 points) Describe how you would measure a voltage in the range of 0 to 1 mV across a 1 MΩ resistor in the frequency range from 100 Hz to 10 kHz, where neither end of the resistor is grounded.
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4.1 (20 points) Sketch your circuit design, including the floor selector circuit, the motor power converter, the elevator motor, the difference amplifier, and any other components that may be necessary.
4.2 (5 points) For G = 100 and 1000, tabulate the voltages at important points in your circuit when the elevator has 5 passengers, the 2nd floor has been selected, and the elevator has come to rest.
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4.3 (5 points) For G = 100 and 1000, tabulate the voltages at important points in your circuit when 5 more passengers enter the elevator (total = 10) while the floor selector circuit is still set to the 2nd floor. Describe any motion of the elevator relative to 4. above.
4.4 (5 points) For G = 100 and 1000, tabulate the voltages at important points in your circuit when all passengers get off the elevator while the floor selector circuit is still set to the 2nd floor. Describe any motion of the elevator relative to 4.3 above.
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Problem 5 (34 points)
Design a circuit for controlling a street light. The street light is to be turned on at night and turned off during the day. Components available are:
- PIN photodiode
- Street light (200 V, 10 A)
- Electromechanical relay switch (input 10 V at 1 A, output 200 V at 10 A)
- Additional components as needed, but keep it simple
5.1 (18 points) Sketch your design, showing and labeling all essential components and interconnections.
5.2 (5 points) List voltages at key points in the circuit at night.
5.3 (5 points) List voltages at key points in the circuit during the day.
5.4 (6 points) Describe three important common-sense considerations for mounting the PIN photodiode.
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Problem 6 (24 points)
You have just been hired to design a sensor for a new class of icebreaker ship. These ships are used to smash their way through sheets of floating ice, either to get to a destination, or to clear a passage for other ships. The hull (outer structural surface) is very thick and strong, but the ship’s engines are powerful and it is possible to damage or destroy the hull by driving it against large floating slabs of thick ice. The plan is to provide the captain of the ship with a continuous monitor of the shear on the hull at the water line. The shear is the difference between the strain a few feet below the water line (where the ice is pushing against the moving ship) and the strain a few feet above the water line (where there is no ice). When the ice becomes thicker or the slabs become larger, the engine speed can be reduced to avoid damage to the hull.
Bow
Stern
Screw
Waterline Ice
Bridge
Design a system that
- Senses the difference in strain S+ – S– on the hull between a few feet above the water line S+ and a few feet below the water line S–
- Provides an analog signal proportional to S+ – S– such that an output of 5 V corre- sponds to S+ – S– = 0.1%.
- Provides filtering suitable for the signal and noise frequencies that you would anticipate.
- Displays the value of the shear on the ship’s bridge (control room)
Assume that the temperature of ice-laden sea water is constant (28°C) so you do not have to compensate for changes in temperature.
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Equations, some of which you may need:
V 1 V 1 + V 2
R 1
R 1 + R 2
R ( T ) = R ( T 0 )exp β (^) T^1 − (^) T^1 0
V rms = B ( D 1 G )
2
+ ( D 0 )
V(t) = V 0 sin(ωt) ω = 2 πf V 0 = A(V+ − V− )
G =
1 + ( f / fc )
2 n
tan
φ n
=^
f fc
N ( x ) = N (0) e − x μ
x = e −α t^ [ A cos(ω t ) + B sin(ω t )] = R e −α t^ cos(ω t +δ) V = q / C
v = v 0 + a t x = x 0 + v 0 t + 0.5 at^2 (constant a ) g = 10 m s–
T = T 2 − ( T 2 − T 1 ) e − t^ /^ τ^ I = I 0 e − kLC^ ∆ x^ =^
∆ V
dV / dx
I rms = 2 qI ( F 2 − F 1 ) q = 1.60 x 10–19^ Coulombs
V rms = 4 kTR ( F 2 − F 1 ) k = 1.38 x 10–23^ Volt^2 sec ohm–1^ °K–
RT = R 3
Vb R 1 − V 0 ( R 1 + R 2 ) Vb R 2 + V 0 ( R 1 + R 2 ) V^0 =^ G ±( V +^ −^ V −^ )^ +^ Gc^ ( V +^ +^ V −)
fc =
2 π RC
“CMRR” =
G ±
Gc
“CMR”= 20 log 10
G ±
Gc
R = ρA / L
∆R
R
= Gs
∆L
L
V 0 = Vb Gs
∆L
L
VT = V BE 2 − V BE1 =
kT q
ln
I 1
I 2
k^ / q^ =^ 86.17^ μV/ K
PR =σ AT^4 σ = 5.6696 × 10 −^8 W m−^2 K 4
E = hc /λ hc = 1240 eV ⋅nm λmax = (2.8978 × 106 nm K) / T
η=
Tn + 2 − Tn + 1 Tn + 1 − Tn
T equ = Tn + 1 +
Tn + 2 − Tn + 1 1 −η
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Q = π I + I^2 R / 2 + K (^) p ( Ts − T 0 ) + K (^) a ( Ta − T 0 ) Tequ =
π I + I^2 R /2 + K (^) pTs + K (^) aTa K (^) p + Ka
μ ≈ a = (^) m^1 ai i = 1
m
∑ σ a
m − 1 (^ ai^ −^ a )
2 i = 1
m
∑ σ^ a =
σ a m
σ (^) f =
∂ f ∂ a 1
2 σ a^21 +
∂ f ∂ a 2
2 σ a^2 2 + +
∂ f ∂ an
2 σ an^2
Johnson noise = 129 μV for 1 MHz and 1 MΩ
Iron+Constantan - 52.6 μV/°C W+W(Rh) - 16.0 μV/°C
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