Electronic Instrumentation

Electronic Instrumentation Test Information (ENGR-4300)

Last Updated January 2009

Quiz Information

Quiz Dates

Quiz 1: Thursday, February 18
Quiz 2: Thursday, March 4
Quiz 3: Thursday, April 8
Quiz 4: Thursday, April 29

Crib Sheets

Quiz 1
Quiz 2
Quiz 3
Quiz 4

(reserved)

QUIZ 1

Quiz 1 2009 Spring solution
Quiz 1 2008 Fall solution
Quiz 1 2008 Spring solution
Quiz 1 2007 Fall solution

You will have two hours

Five Questions each worth about 20 points

Question 1 -- Circuit Analysis

Be able to handle combinations of parallel and/or series resistors
You may be asked to give resistance expressions in equation form, rather than as a number.
Be able to find voltages or currents through any resistor
Be able to find the total resistance or current
Know the voltage divider equation.
Be able to find the voltage across a resistor in a voltage divider configuration.
The following file has past test questions on this topic: CircuitAnalysis.pdf

Question 2 -- Filters

Understand how capacitors behave at very low and high frequencies.
Understand how inductors behave at very low and high frequencies.
Be able to redraw a given RL, RC or RLC circuit at low and/or high frequencies and identify low pass, high pass, band pass and band reject filters.
Know how to find the resonant frequency of RLC circuits. Remember w=2pf. [omega = 2(pi)f]
Know how to find the corner frequency of RC and RL circuits. Remember w=2pf. [omega = 2(pi)f]
Be able to determine resonant frequency (or w) and corner frequency (or w) given a semi-log plot of the input and output of a circuit.
Be able to identify what will happen to a signal of a certain frequency when it is applied to an RC, RL, or RLC filter. Will the filter pass it, reject it, or do something in between? What will the output voltage be relative to the input voltage?
Remember you can identify the value of a voltage at a point using knowledge of connection to ground, connection to source voltage, location of an open circuit, location of a short, or the voltage divider rule.
The following file has past test questions on this topic: Filters.pdf
The following file has more test questions with relevance to filters: HighLow.pdf

Question 3 -- Transfer Functions and Phasors

Be able to apply the voltage divider equation and parallel and series combination rules to find transfer functions using complex impedance expressions. Also be able to simplify these expressions.
Be able to simplify the transfer function to find a function which governs behavior at low and high frequencies.
Be able to find the magnitude and phase of the simplified transfer function at low and high frequencies.
Be able to to simplify the transfer function to find a function which governs behavior at the corner or resonant frequency.
Be able to find an expression (or value) for the magnitude and phase of the simplified transfer function at the corner or resonant frequency.
Be able to use the transfer function to determine the output amplitude and output phase of a circuit given the input amplitude, input phase, and frequency.
Be able to identify low pass, high pass, band pass and band reject filters given a plot of the transfer function.
Be able to sketch magnitude and phase for low pass, high pass, band pass and band reject filters using their behavior at low frequencies, high frequencies and the resonant or corner frequency.
Be able to determine resonant frequency (or w) and corner frequency (or w) given a semi-log plot of the transfer function of a circuit.
Don't forget the simple substitution of short and open circuits for capacitors and inductors. It is an easy way to double check transfer function behavior at low and high frequencies.
The following file has past test questions on this topic: TransferFunctions.pdf

Question 4 -- Transformers and Inductors

Know the basic equations involving transformers and how to apply them.
Know the basic characteristics of transformers.
Be able to calculate an unknown inductance given the capacitance or capacitance given the inductance.
Be able to calculate the resonant frequency given inductance or capacitance...or visa versa.
Be able to estimate the inductance of a coil when given some dimensions for the unknown inductor from the ideal formula.
Know whether or not this ideal formula will over estimate or under estimate the inductance of the coil.
The following file has past test questions on this topic: Transformers.pdf
The following file has past test questions on a combination of related topics: Inductance.pdf

Question 5 -- PSpice, Instrumentation and Components

Be able to identify which trace on a plot corresponds to which voltage point of a simple circuit.
Given a PSpice plot with time-varying signals on it, show that the signals satisfy the appropriate voltage and current relationships.
Given that you wish to obtain a particular AC Sweep, DC Sweep, or Transient analysis with PSpice, describe the specific steps you would follow. You will be given blank windows and asked which ones you will use and what numbers you will input.
Given an image of one of the instruments we have used in this class (function generator, digital multimeter, scope, dc supply), identify the buttons you would push for some specified purpose. Only the most basic functions will be considered.
Understand how to set frequency, amplitude, dc offset, and duty cycle on function generator.
Describe how to use the multimeter to measure voltage and resistance.
Describe how to set the correct voltage with the DC supply.
Understand how to set time and voltage scales on the 'scope.
Understand how to determine voltage values or time values using Voltage/Time buttons and/or scale factors on the 'scope.
Understand how to subtract two signals or set up a simple Lissajous figure on the 'scope.
Be able to explain the discrepancy between reading on the 'scope (or the DMM) and the function generator and why it happens.
Be able to read resistors and capacitors and find tolerances.
Know when equipment impedances and resistance of wires can and cannot be ignored.
The following file has past test questions on these topics: General.pdf

Additional Topics

The following additional topics may also be covered as parts of the above five questions.

Sine Waves

Given an exact image produced on the oscilloscope, determine the mathematical representation of the signal displayed.
Be able to find peak-to-peak amplitude, RMS amplitude, amplitude phase, frequency, angular frequency, period, and dc offset
Know all units for the above.
Be able to sketch a sine wave from the mathematical equation

Homeworks and Experiments

Any question included in a Report and Conclusions section of experiments 1-3 is fair game.
Any question similar to those on homeworks 1-3 is fair game.

Other Skills

Be able to read semi-log plots.
Be able to substitute in numerical values for R, L, C and w=2pf as needed to find numerical answers.

Quiz 1 Samples

Review Sessions

The class before the quiz - we will solve a test that has some similarities to the quiz you will take.

Crib Sheet

The following crib sheet will be provided.

QUIZ 2

Quiz 2 Spring 2009 solution
Quiz 2 Fall 2008 solution
Quiz 2 Spring 2008 solution
Quiz 2 Fall 2007 solution

You will have two hours

Five Questions each worth about 20 points

Question 1 -- Damped Sinusoids and the Strain Gauge Bridge

Know the equation for a damped sinusoid.
Be able to determine the damping constant of a damped sinusoid given a plot.
Be able to find other properties of a damped sinusoid: initial amplitude, frequency, period, angular frequency, and DC offset.
Be able to identify passive circuits (no input voltage source) that produce sinusoids (LC) and damped sinusoids (RLC). Be able to relate the component values of these circuits to the properties of the sinusoid. The resonant frequency (in Hertz) is given by f=1/[2psqrt(LC)] and the damping constant (in 1/sec) is given by a=R/[2L].
Know what a bridge circuit is and how it is used in the experiments.
Know what a balanced bridge is and how to recognize a circuit that is balanced.
Know how to apply the equation that relates the frequency of a loaded beam to the mass at the end of the beam.
The following file has past test questions related to damped sinusoids: DecaySine.pdf

Question 2 -- Thevenin Equivalent Sources

Be able to apply Thevenin equivalent method to a voltage divider, a Wheatstone Bridge or other simple configuration.
Be able to find the Thevenin resistance
Be able to find Thevenin voltage
Be able to draw the Thevenin circuit with or without a load
Be able to use a voltage divider to determine voltage across a load placed on the Thevenin equivalent circuit.
The following file has past test questions on finding Thevenin Circuits: Thevenin.pdf

Question 3 -- Op Amp Applications

Know how to recognize the amplifier configurations we have already seen: inverting, non-inverting, buffer, differentiator (real and ideal), integrator (real and ideal), differential, and (weighted) adder.
Know the characteristic equation (in the time domain) that governs each circuit above.
Know the transfer function (in terms of j and w) that governs each circuit above.
Know the characteristics and limitations of op-amps.
Know what a voltage follower (buffer) is and why you would want to use it in a circuit.
Know how to apply the characteristic equation of an op amp to find the gain, input voltage, output voltage or resistances given the other values.
Understand how to find an equation for the behavior of a circuit involving more than one op-amp circuit in series: H_total = H₁ * H₂.
Understand how to apply the equation for the combined behavior of an op-amp circuit to digital-to-analog conversion or other task.
The following file has past test questions on digital to analog conversion: DigitalAnalog.pdf
The following file has past test questions with relevance to op-amp applications: OpAmp-Applications.pdf

Question 4 -- Op Amp Analysis

Know how to use the op amp equations to derive the transfer function for all of the amplifier circuits studied: inverting, non-inverting, buffer, differentiator, integrator, differential, and (weighted) adder.
Know how to use the op amp equations to derive the transfer function for a simple circuit similar to the above.
The following file has test questions with relevance to op amp analysis: OpAmp-Analysis.pdf

Question 5 -- Integrators/Differentiators

Be able to sketch or recognize the output of a simple op-amp circuit given the input. Note that we are especially interested in the amplitude and phase effects of integrators and differentiators.
Know the basic mathematical concepts behind differentiation (slope of curve) and integration (area under curve).
Know that real integrators and real differentiators only work well at certain frequencies.
Be able to recognize the characteristic curve (sweep of magnitude and/or phase) of both integrators and differentiators.
Be able to identify frequencies at which integrators and differentiators are working more-or-less correctly given an AC sweep of the transfer function magnitude or phase.
Know how to apply the equation for the corner frequency of an integrator or a differentiator to determine an estimate of when these circuits will be acting ideally and when they will be acting like an inverting amplifier.
The following file has test questions with relevance to op amp analysis: OpAmp-DiffInt.pdf

Homeworks and Experiments

Any question included in a Results and Discussion section of experiments 4-5 are fair game.
Any question similar to those on homeworks 4-5 is fair game.

Basic Skills

Basic skills related to PSpice, Equipment, and Sine Waves may appear on this, or any other, exam.
See the list for quiz 1 for details.
The following file has past test questions on these topics: General.pdf

Other Skills

Know the voltage divider equation.
Be able to find the voltage across a resistor in a voltage divider configuration.
Be able to apply the voltage divider equation to transfer functions with complex impedance expressions.
Be able to identify the value of a voltage at a point using knowledge of connection to ground, connection to source voltage, open circuit, short, or voltage divider rule.
Be able to read semi-log plots.
Be able to substitute in numerical values for R, L, C and w=2pf as needed to find numerical answers.

Quiz 2 Samples

Review Sessions

The class before the quiz - we will solve a test that has some similarities to the quiz you will take.

Crib Sheet

The following crib sheet will be provided. We will also give you the crib sheet from the first quiz.

QUIZ 3

Quiz 3 Spring 2009 solution
Quiz 3 Fall 2008 solution
Quiz 3 Spring 2008 solution
Quiz 3 Fall 2007 solution

Five Questions each worth about 20 points

Question 1 -- Astable Multivibrators (555-Timers)

Be able to apply the equations for T1, T2 and frequency given R1, R2 and C.
Be able to find values of R1, R2 or C given T1, T2 or frequency.
Given a plot of the output of an astable multivibrator circuit, be able to determine T1, T2, T and frequency. Also be able to use these to find values for R1, R2 and/or C.
Be able to find the equation for duty cycle and understand how it is related to the resistor values.
Be able to recognize the output plots for pins 3(output), 2(trigger), 6(threshold) and 7(discharge). Also know the pin names.
Be able to sketch the output (3), the capacitor voltage (2,6), and the discharge (pin 7) of a 555-timer circuit in astable mode vs. time. If you are given values for R1, R2, C and the source voltage, you should know the voltage range of the signals at pin (2,6) and 3. You also be able to estimate the signal at pin 7.
Be able to find the decay constant for the charge and discharge cycles of the capacitor in the astable miode circuit.
Understand how the pulses from an astable multivibrator circuit can be used to do pulse width modulation.

Question 2 -- Combinational Logic Circuits

Be able to identify the following logic gates: AND, OR, NAND, NOR, XOR (EOR), XNOR, NOT.
Know the truth tables for the following logic gates with up to four inputs: AND, OR, NAND, NOR, XOR (EOR), XNOR, NOT.
Be able to draw a truth table or timing diagram for a digital circuit.
Be able to recognize or sketch the output timing diagram of a digital circuit.
Know the PSpice conventions for naming the input and output pins of logic gates.
Be able to use Boolean algebra to describe the overall or relative function of a digital circuit.
Be able to simplify simple Boolean algebra expressions.
Be able to name a NAND gate or other circuit as equivalent to one of the logic gates above.

Question 3 -- Sequential Logic Circuits

Be able to identify or sketch the output of a counter or a J-K flip-flop.
Be able to draw a truth table for a J-K flip-flop.
Understand how a flip-flop can be used as a memory device.
Understand how many bits each counter has, what behavior each bit exhibits, and how to string counters together to count higher.
Know what the function of the clock is in the flip flop and counter.
Understand the effect of clock pulse timing can have on flip-flop outcome.
Understand the function of the clear signal to counters and flip-flops.
Know what a race condition is and how to prevent one.
Understand how to string flip-flops together to make a counter.
Be able to recognize or sketch the output timing diagram of a sequential logic circuit given the clock signal.
Understand what a clock is and what it looks like in PSpice.

Question 4 -- Schmitt Triggers and Comparators

Understand the difference in function between a comparator and a Schmitt trigger in the presence of noise.
Be able to sketch the output from a comparator and Schmitt trigger from a given input.
Be able to identify the point at which a Schmitt trigger will switch when voltage is increasing and decreasing.
Be able to define hysteresis.
Understand the relationship between hysteresis and when a Schmitt trigger switches.
Understand the model of a Schmitt trigger explained in class and in your book. Be able to find the switching thresholds and hysteresis of a circuit using this model.
Be able to determine hysteresis of a Schmitt trigger from a plot of Vin vs. Vout and/or Vout vs. time.
Understand what saturation of an op-amp is and how it relates to the function of comparators and Schmitt triggers.
Be able to recognize, identify, and sketch traces from comparators and Schmitt triggers.
Be able to calculate voltages at different points in a switching circuit with comparators and Schmitt triggers.

Question 5 -- Switching Circuits

Know how to model a transistor as a switch.
Know how to draw the "diode" model of a transistor.
Be able to define and identify the base, emitter and collector of a transistor.
Be able to recognize, identify, and sketch traces from a simple circuit involving transistors, comparators, Schmitt triggers and/or relays.
Be able to redraw a simple circuit using the switch or diode model of a transistor.
Be able to redraw and analyze a circuit when a relay is in either position.
Be able to calculate voltages at different points in a simple switching circuit.
Be able to identify a combinational logic gate given a simple transistor model.

Digital skills

Know which voltage levels correspond to ON and OFF in Digital Electronics.
Review the binary numbering system.
Be able to convert between decimal and binary and back.

Quiz 3 Sample Questions

Flip Flops and Counters FlipFlopCount.pdf
Logic Gates LogicGates.pdf
Schmitt Triggers and Comparators Schmitt.pdf
555 Timers Timers.pdf
Transistor and Relay Circuits TransistorRelay.pdf
Quiz 3 crib sheet now available

Quiz 3 Samples

Review Sessions

The class before the quiz - we will solve a test that has some similarities to the quiz you will take.

Crib Sheet

The following crib sheet will be provided. You will also receive a copy of the crib sheets for quizzes 1 and 2.

QUIZ 4

Quiz 4 Spring 2009 solution
Quiz 4 Fall 2008 solution
Quiz 4 Spring 2008 solution
Quiz 4 Fall 2007 solution

Five Questions each worth about 20 points

Questions 1 and 2 -- Diodes: Rectifier Circuits and Limiter Circuits

Understand the i-v characteristic curve for diodes (and Zener diodes). Know the terminology and characteristics.
Be able to recognize full-wave rectifiers, half-wave rectifiers, smoothing circuits, regulators and limiters (clippers) from their circuits or characteristic plots.
Understand the effect that the threshold voltage of the diode(s) has on output of the above circuits.
Understand how the output of the above circuits would look for signals with input voltages of different amplitudes.
Be able to sketch a plot of the output voltage vs. the input voltage for the above circuits.

Question 3 -- Zener Diodes

Understand the effect Zener diodes have in a limiter or voltage regulator.
Know how to interpret output plots for inputs of different voltage levels in circuits involving Zener diodes.
Be able to determine output voltage levels for different input voltages in a Zener diode circuit.
Understand the i-v characteristic curve for and Zener diodes. Know the terminology and characteristics.
Be able to approximately reproduce or identify the plots Zener diode voltage regulation. Note that both DC sweep and transient analysis were asked for.

Question 4 -- LEDs and Phototransistor Circuits

Understand the proper configuration of LEDs in circuits and how they operate.
Understand the proper configuration of phototransistors in circuits and their operation.
Be able to calculate voltages and currents in circuits containing these devices.

Question 5 -- Circuit Functionality: Signal Modulation and Filtering

Be able to identify blocks in a circuit.
Circuit blocks you have seen

Basic Circuits (voltage dividers, components in series and in parallel, resistance bridges)
Filters (low pass, high pass, band pass, band reject)
Transformers
Op-Amp Amplifiers (inverting, non-inverting, adder, differential)
Voltage followers (also called buffers)
Op-Amp integrators and differentiators
555-Timer (astable, monostable, modulator)
Logic gates (AND, NAND, OR, NOR, XOR, XNOR. NOT) sequential logic (counters and flip flops)
Comparators and Schmitt triggers
Transistors
Diodes (half wave rectifier, full wave rectifier, limiter, regulation)
Zener diodes (limiter, voltage regulation)
Voltage sources (DC, AC, square waves, triangular waves)
Miscellaneous (dc-blocking capacitors, by-pass capacitors, speakers)

Be able to identify blocks identify or infer the output of a circuit block given the input.
Be able to determine the behavior of a circuit block. (ie. This block is an inverting amplifier. The feedback resistor is 20k. The input resistor is 1K. It will invert the input and multiply it by a factor of 20.)
Be able to infer how a circuit block will behave at certain frequencies. (i.e. I know the corner frequency of this low pass filter is fc=1/(2pRC). If I substitute in the component values I get fc = 5K Hz. If the input frequency is 20K hertz, the filter should block the input entirely and the output should be zero. If the input frequency is 1K Hz, the filter should allow the input to pass and the output will be equal to the input.)

Quiz 4 Sample Questions

Diodes Diodes.pdf
Zener Diodes Zeners.pdf
Digital to Analog Conversion: DigitalAnalog.pdf
Circuit Functionality CircuitFunctionality.pdf
Quiz 4 crib sheet now available

Quiz 4 Samples

Review Sessions

The class before the quiz - we will solve a test that has some similarities to the quiz you will take.

Crib Sheet

The following crib sheet will be provided. You will also receive a copy of the crib sheets for quizzes 1-3.