Design, implement, and test a timer (Prototype Product)

| April 17, 2015

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Design, implement, and test a timer (Prototype Product)

 

 

 

 

 

 

 

 

 

 

 

 

 

Important

 

  • Make sure that you sign the attendance record for each session.

 

  • You will use the same breadboard for the rest of this semester. Mark your breadboard and hand it to the technician at the end of each session.

 

  • You must have a lab logbook and you will need it for each practical session.

 

  • Record your activities and results on your logbook. ‘Book keeping’ is an essential part of the training.

 

  • You are required to submit your logbook at the end of this semester, together with your report.

 

  • You must show your final prototype product to your tutor by the end of the last session.

 

 

 

 

Part 1: Project Management Skills

 

Aims

  • To learn how to prepare a question list following a customer inquiry
  • To practice on interpreting customers’ needs and taking action accordingly
  • To gain experience in developing preliminary product specification  To practice on project planning by drawing Gantt chart

Tasks and requirements:

 

  1. Preparing a question list following the customer inquiry:

 

A manufacturing company, ABC Ltd, made the following inquiry:

“Please could you give me a quotation for an electronic timer? We need it for controlling our chemical processes.”

 

To gather more information from the customer, prepare a question list directly on your logbook. Avoid using loose paper.

 

Compare your list with other students’ list and learn from each other.

 

  1. Interpreting raw data and taking Action

 

Based on the given question list and the answers from your customer,

  • Try your best to convert the raw information into specific data.
  • For each question, write down one or two sentences for ‘Action’ to be taken.

 

 

  1. Developing a preliminary specification

 

  • Part I:        Product description
  • Part II:       Features (Bullet points)
  • Part III:      Circuit Diagrams — To be developed
  • Part IV:      Ratings (Table) in the following style,

 

Parameters Values Units
DC output voltage 5 V

 

  1. Planning: Gantt Chart

 

Horizontal direction: Time

Vertical direction: Tasks

 

Indicative Tasks:

  • Concept generation o Concept selection o Cost estimation o Top-down design o Simulation o Testing
  • Add your own tasks

 

 

 

 

 

 

Part 2: Design and test of amplifier

 Aims

  • To build an amplifier
  • To evaluate its performance
  • To learn the function of components through testing
  • To improve your knowledge of amplifier through ‘real’ experiments  To strengthen your practical skills

Components & Equipment

Equipment: Breadboard, DC Power Supply Unit (PSU), Digital MultiMeter (DMM),

Oscilloscope

Components: Resistors (Ω): 51k, 2×5.1k, 1k, 82Ω, Capacitors (nF): 470, 4.7, Transistors:

BC109BP

 

 

Tasks and Experiments

 

  1. Build the following amplifier shown in Fig. 2.1 on breadboard.

 

Fig. 2.1

Here, R1=51kΩ, R2=5.1kΩ, R3=1kΩ, R4=82Ω, and C1=0.47μF. Vs has a frequency of 1kHz.  “a” and “b” represent two nodes.

 

 

 

 

 

 

 

 

 

  1. DC bias point measurement

Set Vs=0V, measure the voltage at nodes a (Va) and b (Vb).

(Q: There are at least two different ways for measuring DC voltages. What are they?)

 

  • Voltmeter
  • Oscilloscope

 

  1. Measuring DC and AC components in a signal Set the magnitude of Vs to 0.1V.

A signal can have DC and AC components: V(Total)=V(DC)+V(AC)

Measure the DC and AC components for

  1. Input voltage
  2. Vb(Total)

(Hint: Use different coupling)

For the V(AC) and V(Total), you should record the peak value.

In you logbook, record the following waveforms:

  1. One diagram for Vb(Total), Vb(AC), and Vb(DC)
  2. One diagram for Vs(AC) and Vb(AC)

 

Analysis: Leave one blank page in your logbook and do the following when you have time

  1. Determine the AC voltage gain, A
  2. Explain the phase difference between Vs(AC) and Vb(AC)

 

 

  1. Investigate the function of R1
    1. Disconnect R1
    2. Measure Vb(Total) and Vb(AC)
    3. Comment on the change of Vb and the function of R1

 

 

  1. Study the function of C1
    1. Reconnect R1
    2. Take out C1 and connect Vs directly to node ‘a’
    3. Measure Vb(Total) and Vb(AC)
    4. Comment on the change of Vb and the function of C1.

 

 

  1. Investigate the function of R3
    1. Reconnect C1
    2. Increase R3 to 5.1kΩ
    3. Measure Vb(Total) and Vb(AC)
    4. Comment on the change of Vb and the function of R3.

 

 

  1. Find the limitation on input voltage
    1. Reset R3 to 1kΩ
    2. Monitor Vs(AC) and Vb(AC) by an oscilloscope
    3. Increase Vs gradually to 0.3V
    4. Record the waveform of Vb(AC) and Vb(Total)
    5. Measure the maximum value of Vb(Total)
    6. Comment on the change in Vb(AC) and the maximum value of Vb(Total).

 

 

  1. Explore the effect of input frequency
    1. Reset Vs to 0.1V.
    2. Change the input frequency between 10Hz and 1MHz. For each frequency, record the peak value of Vb(AC)

Q: How to select the frequency point?

  1. Determine the AC voltage gain, A
  2. Plot A against frequency

Q: Do you use linear or logarithmic scale?

  1. From your results, determine F1.

Definition of F1: When frequency≤F1, A≤0.707A(Max)

Q: How do you determine F1, if there is no data point at A=0.707A(Max)

Part 3: Design and test of oscillator

Aims

  • To build an oscillator based on NOR gates
  • To evaluate its performance
  • To find how to set the oscillating frequency
  • To explore the relation between sound and frequency  To strengthen your practical skills

Components & Equipment

Equipment: Breadboard, DC Power Supply Unit (PSU), Function Generator (AFG), Digital

MultiMeter (DMM), Oscilloscope

Components: Resistors ():  10, 68, 1k, 10k, 2100k, 220k, 620k, 1M, 3.3M, 5.6M, 10M, Capacitors (nF): 10,         100, Transistors and Chips: BC109BP, CD4001BCN, Loud Speaker:

64

 

The CD4001BCN chip has 4 identical, but independent, NOR gates. Each gate has two inputs (Fig. 3.0):

 

Fig. 3.0

 

Tasks and Experiments

 

  1. Construct the oscillator circuit shown in Fig. 3.1 ( R=100k; C=10nF) Do not build the amplifier yet.

 

 

  1. Test the oscillator in Fig. 3.1
    1. Power the chip by applying 9V (DC) between pin 14 and pin 7
    2. Record the waveform of Va, Vb and Vc
    3. Measure the oscillation frequency

 

 

 

 

  1. Interfacing with the amplifier in Fig. 3.1

Build the amplifier in Fig. 3.1. Note the layout of the three terminals for transistor.

R(load)=64 is the loud speaker.

Link the oscillator with the amplifier by connecting the dashed line Do you hear anything?

 

 

  1. Estimate the power delivered to the R(load)

Many loud speakers have impedance of 8. Follow the steps below to estimate the power delivered to an 8 loud speaker:

 

  1. Replace the loud speaker with a resistor, R(load)=10 (available in the lab).
  2. Record the waveform of voltage drop across R(load): V(load)
  3. Measure the top level of V(load), V(top)
  4. Calculate the delivered power by using: P=V2(Top)/[2R(load)] Q: Why is there a factor ‘2’ in the formulae?

 

Warning!

For small R=10, the transistor will be hot. Do not touch it.

 

 

 

Fig. 3.1

 

  1. Investigate how the power affects the amplitude of sound
    1. Reduce the power supply from 9V gradually
    2. Monitor the corresponding reduction of V(Top)
    3. Note the change in the amplitude of sound

 

 

  1. Study the effect of component value on oscillation frequency and sound quality For  R=1k, 10k, 620k, 3.3M, do the following:
    1. Monitor Vc
    2. Measure the frequency
    3. Comment on how frequency affects the quality of sound

 

 

  1. Improve the tune

Reset R=100k. (R in Fig. 3.1 is renamed as R4 in Fig. 3.2)

 

 

Build the circuit given in Fig. 3. 2.

 

Does it sound better?

 

 

  1. Effects of component value on the tune Use R7=620k, 5.6M, and 10M.

Comment on how the tune changes.

 

Q: Explain why we use 64 loud speaker, instead of 8

 

 

Fig. 3.2

 

 

 

4005ELE – 

Electrical Engineering Practice 1

 

 

Part 4: Design and test of delay unit

Aims

  • To explore the property of 555 chip through experiments
  • To design and test a Voltage Controlled Oscillator (VCO)
  • To build a 555-based delay unit
  • To design and build a trigger circuit  To strengthen your practical skills

Components & Equipment

Equipment: Breadboard, DC Power Supply Unit (PSU), Digital MultiMeter (DMM),

Oscilloscope

Components: Resistors (Ω): 330kΩ, 200k, 5×100k, 2×5.1k, 1k, 82, Capacitors (F): 10n, 22n

100μ(Tantalum), Chips : LMC555CN (see the enclosed circuit), LEDs: LED, Switch: On/Off Switch

 

 

 

Tasks and Experiments

 

  1. Design and build a 555-based oscillator Build the circuit shown in Fig.4.1.

 

 

 

Fig. 4.1

 

Test 1

  1. You should record both maximum and minimum values for V2 and Vout. The durations for Vout=‘high’ and ‘low’ and the period of the signal should also be recorded.

 

  1. Compare the waveform of Vout with the waveform of Vc for the NOR gate based oscillator. What is the difference?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Test 2

  1. Increase RA to330kΩ and repeat the step (a) of test 1. How do the durations for Vout=‘high’ and ‘low’ change?

 

  1. Reset RA=100 kΩ and change RB to 330kΩ. Repeat the step (a) of test 1. How do the durations for Vout=‘high’ and ‘low’ change?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Based on your experiments, analyse why the waveform of Vout here is different from the waveform of Vc for the NOR gate based oscillator. You may delay this analysis until you finish all the experiments.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Test 3

  1. Set RA=RB=100kΩ and reduce the supply voltage, Vcc, to 6V
  2. Repeat the measurement in the step (a) of test 1

 

 

 

 

 

Test 4

  1. Reduce the supply voltage, Vcc, to 3V
  2. Repeat the measurement in the step (a) of test 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Based on your results of tests 3 and 4, find the relation between Vcc and the followings:

  1. The maximum value of V2
  2. The minimum value of V2
  3. The maximum value of Vout

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. 555 chip as a voltage controlled oscillator (VCO)

You have built oscillators based on both NOR gate and 555 chip. A main difference between these two is that 555 chip allows the frequency to be controlled electrically, while NOR gate does not.

 

Tests

  1. Set Vcc=9V
  2. Apply a voltage to pin 5, V5
  3. Change V5 between 0 and 8V in step of 1V

 

 

 

 

 

 

 

 

 

 

For each voltage level, do the followings:

  1. If there is no oscillation, go to next voltage level
  2. Record the minimum and the maximum value of V2
  3. Record the maximum value of Vout and its frequency

 

Evaluation and Analysis

  1. Plot V2(Maximum), V2(Minimum), Vout(Maximum), and frequency against V5
  2. Explain why the frequency changes with V5

 

 

  1. The delay unit
    1. Build the circuit shown in 4.2. Where is your triggering circuit?
    2. Close the switch and record your time
    3. After a delay, the LED should be switched off by the delay unit
    4. Double the R to 200kΩ, what happens to the delay?

 

Fig. 4.2

 

R=R1=R2=100kΩ, C=100μF (Tantalum Capacitor), C1=22nF

 

Q: If the delay is not 10sec when R=100kΩ, how can you adjust it to 10sec?

 

 

4005ELE – 

Electrical Engineering Practice 1

 

 

Part 5: Put it together and calibration

Aims

  • To interface the delay unit, oscillators and amplifier
  • To calibrate the system
  • To strengthen your practical skills

 

Components & Equipment

Equipment: Breadboard, DC Power Supply Unit (PSU), Battery: 9V with connectors, Digital

MultiMeter (DMM), Oscilloscope, Screwdriver

Components: Resistors (Ω): 10k, 300k, 5×620k, Capacitors (F): 33μ, Potentiometer (Ω): 50k linear Carbon, Multi-position switch

Note: All resistors are of 0.25W Metal Film (: 1%)

 

 

 

Experiments

 

  1. Interfacing

 

Input

 

Output

 

                Control              Signal

Fig. 5.0

Q1: To disable the above NOR gate, should the ‘control signal’ be ‘high’ or ‘low’?

(Hint: Use the logical properties of NOR gates)

Q2: What is the output of the delay unit (pin 3 of 555) before the required delay is reached?

 

Connect your delay unit and the oscillator as shown in Fig. 5.1

 

  1. Calibration

 

 

  • V1R1
  • V2

 

R2

3 3

 

If the pointer moves up, R1 reduces and R2 increases. It is often used as a variable voltage divider: V2=V1 × R2/(R1+R2)

  1. Connect the given potentiometer as shown in 5.2
  2. For R3=620kΩ, adjust the delay to 60sec (Note: there is no commercial resistor with a value of 600kΩ)
  1. Design of variable resistors for the delay unit

 

Delay(min) 0.5 1 2 3 4 5
R3(k) 310 620 1240 1860 2480 3100

 

There is no commercial 310k. How can you obtain one?

 

Build the circuit given in Fig. 5.3 by using a multi-position switch. Test and record the delay for each value of R3.

 

  1. Replace the power supply unit by a 9V battery

Use battery and add C5 to the circuit, as shown in Fig. 5.4.

 

Q1: What is the function of C5?

Q2: Why do we use two switches (S1 and S2)?

 

 

 

 

Fig.5.1

 

                   IC1:  LMC555CN     IC2:  CD4001BCM  Quad NOR Gates

Fig.5.2

Pin 6 or 7                               +9V

of 555                                          Fig.5.3

Fig.5.4: Final ciruit

 

4005ELE – 

Electrical Engineering Practice 1

 

 

Part 6: Veroboard design and package

 

Aims

  • To practice on designing circuit layout
  • To practice on assembly
  • To improve soldering skills
  • To test your unit
  • To produce a prototype product  To strengthen your practical skills

Components & Equipment

Equipment: Breadboard, DC Power Supply Unit (PSU), Oscilloscope, Screwdriver, Drill, Soldering tools, 1 Veroboard, 1 Box, 4 Bolts and Nuts, double-side tapes, Labels

 

 

Tasks and Experiments

 

  1. Design the circuit layout for veroboard
  2. Transfer your circuits to veroboard
  3. Tests before boxing
  4. Boxing (i) How do you support your veroboard in the box?
    1. How do you secure the off-board components?
    2. How do you design the front panel display?
  5. Final tests
  6. Submit your box to your tutor
  7. If you finish earlier, write an instruction menu for your ‘product’.

 

 

 

 

 

Congratulations on your 1st prototype product at Liverpool JMU!

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