At-Home Lab Kit

1
At-Home Lab Kit

• Advisor Dr. Raymond Winton
• Professor of Electrical Engineering
• Mississippi State University

2
Team Members

• Josh Durr (Team Leader)
• Kelly Massa

• Steve Miller
• Steven Nichols

3
Development Reason

• To be able to provide instructors and students an
  inexpensive and portable means to instruct and do
  home projects. At this time there is no such
  equipment that meets this criteria.

Solution to Problem

• To design and develop a small, inexpensive lab
  kit. This lab kit will include a function
  generator and a digital oscilloscope. This will
  allow instructors and students to complete their
  work at their leisure.

4
Design Constraints

• To produce three waveforms with a variable
  frequency of 0 Hz-100 kHz and a variable
  amplitude of 0 9 V.
• To have a frequency response of less than 5
  variation.
• To produce the three waveforms with a signal to
  noise ratio of greater than 60 dB.
• To have a load capability of up to 1 M-ohms.

5
Design Constraints Cont

• To manufacture the packaged product for less than
  250 and at a cost to the consumer of less than
  750.
• To power the device using 9V and less than 14
  mA.
• To provide a user interface containing signal
  switches, amplitude variation, frequency
  variation, and a trigger switch.

6
Block Diagram of At-Home Lab Kit
7
Circuitry for Function Generator
Amplitude Adjustment
Wave Shaping Circuitry
Frequency Adjustment
8
Block Diagram of At-Home Lab Kit
9
Oscilloscope

• Hardware
• Power circuitry that will output a -9V, 5V, and
  2V.
• Triggering circuitry that triggers on the
  positive slope.
• Coupling circuitry that couples between AC, DC,
  and GND.
• Software
• Uses an Atmel PIC to control the LCD, and
  calculate and display the pk-pk voltage and
  frequency of the input waveform.
• Monitors and displays the status of the switches
  Volts/Div, Sec/Div, and coupling.
• Displays grid for the determination of the period
  and time constant of the input waveform.

10
State Diagram for Software Protocol
11
State Diagram For Software Monitoring
12
Redesign of Circuitry

• Recalculated the values of the potentiometers to
  raise the voltage range of the output waveforms.
• Redesigned PCB to make the signal to noise ratio
  meet design constraints.
• Redesigned software to make oscilloscope
  compatible with the A/D converter that was
  purchased.

13
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz
Voltage range (Generator)
Frequency Response
Signal to Noise Ratio
14
Limit Test

• Frequency

15
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator)
Frequency Response
Signal to Noise Ratio
16
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator)
Frequency Response
Signal to Noise Ratio
b
17
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V
Frequency Response
Signal to Noise Ratio
b
18
Limit Test

• Voltage

19
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response
Signal to Noise Ratio
20
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response
Signal to Noise Ratio
b
b
r
21
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope
Signal to Noise Ratio
b
b
r
22
Frequency Response
23
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope lt5 lt5
Signal to Noise Ratio
b
b
r
24
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope lt5 lt5
Signal to Noise Ratio
b
b
r
b
25
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope lt5 lt5
Signal to Noise Ratio gt 50 dB
b
b
r
b
26
Signal to Noise Ratio Test for Square
27
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope lt5 lt5
Signal to Noise Ratio gt 50 dB 60 dB 65 dB
b
b
r
b
28
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Frequency Range (Generator) Up to 100 kHz Up to 150 kHz Up to 230 kHz
Voltage range (Generator) Up to 9V 5.4V 8.4V
Frequency Response (/-) 5 of zero slope lt5 lt5
Signal to Noise Ratio gt 50 dB 60 dB 65 dB
b
b
r
b
b
29
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA
Load Capability
Cost
30
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability
Cost
31
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability
Cost
b
32
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg
Cost
b
33
Load Test
34
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg Handles a load of infinity to 50 ohms Handles a load of infinity to 50 ohms
Cost
b
35
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg Handles a load of infinity to 50 ohms Handles a load of infinity to 50 ohms
Cost
b
b
36
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg Handles a load of infinity to 50 ohms Handles a load of infinity to 50 ohms
Cost Man. lt 250 Mark. lt750
b
b
37
Cost Analysis of All Parts
Function Generator XR-2206 4.00
Resistors/Capacitors 3.00 Potentiometers
4.00 Switches 6.00
Digital Oscilloscope PIC 8515 8.00
Resistors/Capacitors 3.00 A/D Converter
7.00 Switches 8.00 LCD Display
90.00 with Controller

• The total parts cost of the PCB is about 140.00
  causing the marketable cost to be about 560.00
• Function Generator contributes about 20.00
• Digital Oscilloscope contributes about 120.00

38
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg Handles a load of infinity to 50 ohms Handles a load of infinity to 50 ohms
Cost Man. lt 250 Mark. lt750 180 720 140 560
b
b
39
Design Constraints vs. Results
Area Design Constraint Prototype Test PCB Test
Power Requirements 9 VDC, lt14 mA 9 VDC, 8 mA 9 VDC 6 mA
Load Capability To handle a resistive load from 100 ohms 1 Meg Handles a load of infinity to 50 ohms Handles a load of infinity to 50 ohms
Cost Man. lt 250 Mark. lt750 180 720 140 560
b
b
b
40
Acknowledgments

• Dr. Raymond Winton
• Dr. J.W. Bruce
• Dr. Picone
• Way Beng Koay
• Dr. Jim Harden
• Mr. Bill Buchanan

41
Questions?
42
References

• 1 Donald A. Neamen, Electronic Circuit
  Analysis and Design 2nd Ed. The McGraw-Hill
  Companies, New York, NY, USA, August 2001
•  
• 2 Roy W. Goody, OrCAD Pspice for Windows
  Volume 1 DC and AC Circuits 3rd Ed. Prentice
  Hall Professional Technical Reference, Columbus,
  OH, USA, August 2000
•  
• 3 Roy W. Goody, OrCAD Pspice for Windows
  Volume 2 Devices, Circuits, and Operational
  Amplifiers 3rd Ed. Prentice Hall Professional
  Technical Reference, Columbus, OH, USA, August
  2000  
• 4 Richard C. Dorf, James A. Svoboda,
  Introduction to Electronic Circuits 5th Ed.
  John Wiley and Sons Inc., New York, NY, USA,
  August 2000
•  
• 5 EXAR Data Book EXAR Corporation, Fremont,
  CA, USA, August 2001
• 6 Metric Test Incorporated, Function Generator
  Prices
• http//www.metrictest.com/, Metric Test
  Incorporated, 2002
• 7 Paul Horowitz, The Art of Electronics
  Cambridge University Press, New York, NY, USA,
  1989
• 8 EXAR Corporation, XR-2206
• www.exar.com/products/xr2206.pdf, EXAR
  Corporation, USA, 2002