Section 1: : Introduction for Workshop Leaders
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Published:1994
Mark Davids, R. Stephen Rea, Paul W. Zitzewitz, 1994. "Introduction for Workshop Leaders", Teaching about Lightwave Communications: An AAPT/PTRA Resource, Mark Davids, R. Stephen Rea, Paul W. Zitzewitz
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The study of lightwave communications is both interesting and relevant to high school students. Most students are interested in CD players, digital tapes, telephones, and other forms of modern communication. This unit is designed to provide students with both the historical and theoretical background information necessary to understand the fundamentals of lightwave communication (see student objectives, p. 2-1). The most important component of this unit is the set of student lab investigations. Starting with simple components, students will build a number of devices that will allow them to understand the mysteries of modern lightwave communications systems.
The study of lightwave communications is both interesting and relevant to high school students. Most students are interested in CD players, digital tapes, telephones, and other forms of modern communication. This unit is designed to provide students with both the historical and theoretical background information necessary to understand the fundamentals of lightwave communication (see student objectives, p. 2-1). The most important component of this unit is the set of student lab investigations. Starting with simple components, students will build a number of devices that will allow them to understand the mysteries of modern lightwave communications systems.
Much of this booklet is based on the work done at the Rutgers National Leadership Institutes for Physics Teachers. The summer institutes allowed high school teachers to learn directly from research physicists from AT&T, Bell Labs, BELLCORE, etc. As a result of these collaborations, various teaching “modules” were developed, including one on “LIGHTWAVE COMMUNICATIONS.” The summer workshops were co-directed by Dr. George Pallrand (Rutgers) and Dr. Sidney Millman, retired director of AT&T Labs. The success of the program was largely due to their personal interest, energy, and unbounded enthusiasm.
This booklet is not intended as a textbook, but rather as a resource and workshop guide. A brief history and a theoretical framework for understanding lightwave communications, student activities, and demonstrations are included. Because much of the technology is relatively new and not included in most textbooks, Sections 3 and 5 should be copied and distributed to students.
The philosophy of this workshop is that students should have a maximum of hands-on learning, and that the equipment should be as simple (and inexpensive) as possible while still working reliably. Additionally, connections need to be made between the simple materials and the complex modern technology of lightwave communications. The physics should be UNCOVERED rather than covered! Teachers and students will find that this unit ties together the topics of sound, light, electric circuits, electromagnetic interactions, and digital communications.
This manual is designed to show you how to run a full day workshop for teachers. When used with your classes, you will find enough material for 6 or 7 class periods. Even though you will need a lot of materials for this workshop, most of the materials can probably be found in your storage area. All are inexpensive and all of the materials can be re-used.
With proper planning, you will have a great workshop!
WORKSHOP CHECKLIST
4 weeks before workshop:
- — 1.
Ask a fellow teacher(s) to help you organize and assist at the workshop. Try to have at least one teacher for each 15 participants.
- — 2.
Reserve a room large enough for your anticipated audience.
- — 3.
Require a deposit from participants at least three weeks before the scheduled event so that you can order enough materials. Give them a deadline and expect almost everyone to wait until the deadline. Remember that your costs will include shipping and handling. Also include the cost of lunch in the workshop.
- — 4.
Order the materials. When ordering by phone, confirm that all needed items are IN STOCK. Order 10% more than needed to cover possible breakage or faulty components. Ask for a guaranteed delivery date.
2 weeks before workshop
- — 5.
Cut and drill the plastic sheet needed for the bias circuits. Cut and drill a few extras and build a few circuits to use as models for the participants.
- — 6.
Solder the telephone microphones to the wires. This is a time-consuming process due to the large heat sink of the microphone.
- — 7.
Inventory the materials as they arrive. Use clear, sealable plastic bags to pack the components for each participant.
- — 8.
Mail a map to all participants. Include a building map, room number, and recommended parking areas. Include the day’s agenda and your home and work phone numbers.
1 week before workshop
- — 9.
Make arrangements for coffee, tea, and donuts and also a simple, but elegant lunch. It is much preferred to eat near the workshop site.
- — 10.
Review this checklist! Time is running out. Try to remain calm. If you have faithfully kept to these timelines you will be ready!
- — 11.
Make sure that all hand tools, wires, glue guns, etc. will be available for workshop.
- — 12.
Have your host personally ask the school’s principal to stop by and either say a few words of welcome or just to see what you are doing.
- — 13.
Call a local newspaper to tell them about your workshop. Briefly describe the purpose and the scope of the workshop. Invite them to send a reporter and photographer for the afternoon session. Most of the construction should be completed by then.
1 day before workshop
- — 14.
Call to confirm your luncheon arrangements.
- — 15.
Bring all of your materials to the workshop sight (if possible) and meet with your co-presenter, host, helpers, etc.
- — 16.
Verify that you will have a working oscilloscope, laser, overhead projector, etc.
- — 17.
Carefully unpack all of the materials. Make sure that all hand tools are available, including soldering irons (with solder and wet sponges), glue guns (with glue sticks), wire strippers, etc.
- — 18.
Put up welcome signs and arrows at the outer entrance doors.
- — 19.
Enjoy a restful night’s sleep.
The BIG DAY
- — 20.
Arrive one hour early to meet with your host, put out the coffee and donuts, etc.
- — 21.
Locate the nearest restrooms and have the custodian unlock them.
- — 22.
Put out a few of already completed reflection photophones and bias circuits as models for the participants.
- — 23.
Plug in the oscilloscopes, lasers, overhead projectors, where they will be used.
- — 24.
Arrange your demonstrations on a front table safely out of the traffic path.
- — 25.
Have participants check in as they arrive and wear a name tag!
SUGGESTED WORKSHOP SCHEDULE
8:30 | Sign in, donuts and coffee |
8:45 | Distribution of workshop manuals and material packets |
9:00 | Welcome and overview of workshop goals |
9:15 | Display of solar cell, amplifier/speaker, reflection photophone, and cheap speaker |
9:20 | Build and test—solar cell, reflection photophone, and cheap speaker |
9:50 | Break to ask questions, discuss problems, etc. |
10:00 | Display of bias circuit and demonstrations using it |
10:10 | Build and Test the Bias Circuit |
11:00 | Break to ask questions, discuss problems, etc. |
11:15 | Demonstrations of response of “grain of wheat” lamp vs. LED on an oscilloscope, AM modulation of microwaves |
11:30 | LUNCH BREAK |
12:30 | Demonstration of internal reflection, electrical interference by spark source, etc. |
12:45 | Discussion of attenuation, sample problems |
1:00 | Cutting and testing the optical fibers |
1:15 | Analog and digital signal theory and worksheets. Shannon’s theory, Nyquist’s theory, the need for more bits and more bandwidth |
1:30 | Analog-to-digital and digital-to-analog game |
2:00 | Demonstration and discussion of channel changer signal with solar cell and oscilloscope |
2:10 | Other methods of digital modulation (CD, bar codes, etc.) |
2:30 | How to “fit the materials into existing curriculum” |
2:45 | Clean up and open laboratory (for those who want to play more!) |
8:30 | Sign in, donuts and coffee |
8:45 | Distribution of workshop manuals and material packets |
9:00 | Welcome and overview of workshop goals |
9:15 | Display of solar cell, amplifier/speaker, reflection photophone, and cheap speaker |
9:20 | Build and test—solar cell, reflection photophone, and cheap speaker |
9:50 | Break to ask questions, discuss problems, etc. |
10:00 | Display of bias circuit and demonstrations using it |
10:10 | Build and Test the Bias Circuit |
11:00 | Break to ask questions, discuss problems, etc. |
11:15 | Demonstrations of response of “grain of wheat” lamp vs. LED on an oscilloscope, AM modulation of microwaves |
11:30 | LUNCH BREAK |
12:30 | Demonstration of internal reflection, electrical interference by spark source, etc. |
12:45 | Discussion of attenuation, sample problems |
1:00 | Cutting and testing the optical fibers |
1:15 | Analog and digital signal theory and worksheets. Shannon’s theory, Nyquist’s theory, the need for more bits and more bandwidth |
1:30 | Analog-to-digital and digital-to-analog game |
2:00 | Demonstration and discussion of channel changer signal with solar cell and oscilloscope |
2:10 | Other methods of digital modulation (CD, bar codes, etc.) |
2:30 | How to “fit the materials into existing curriculum” |
2:45 | Clean up and open laboratory (for those who want to play more!) |
BIBLIOGRAPHY
NOTE - this list will only include USEFUL REFERENCES!!
Magazine Articles
Books
Textbook References
Numerous references to sound, laser discs, am, fm, light
MATERIALS LIST
The following list is organized by the device for which the materials are required. The estimated cost for a complete set of materials for one station is $45, based on quantity discounts listed in the most recent catalogs. The quantities shown are those required for a laboratory of 10 stations or a workshop serving 10 teachers. Consult the appendices of Section 3 for alternative methods of constructing the photophone.
Quantity | Catalog Number | Description | Source | Unit Cost | Total Cost |
1) Commercial Speaker | |||||
10 each | 253-4130 | 3”, 8-Ω speaker | M | 1.83 | 18.30 |
2) Homemade Speaker | |||||
10 each | 5” foam or aluminum plate | local | |||
1 roll | L3-616 | 32 gauge magnet wire | EDL | 2.95 | 2.95 |
10 each | CB-60 | block magnet | TMS1 | 0.90 | 9.00 |
OR | |||||
10 each | 78293C | block magnet | CENCO | 4.95 | 49.50 |
3) Lightwave Receiver | |||||
10 each | 39810 | solar cell | E | 4.35 | 43.50 |
10 each | 277-1008 | miniamp (amplifier/ speaker) | RS | 10.76 | 107.60 |
10 each | 9-V battery (for miniamp) | local | 0.60 | 6.00 | |
10 each | 9-V battery (for miniamp) | local | 0.60 | 6.00 | |
1 roll2 | 515-2100-12-01 | 24 gauge wire (red) | M | 3.94 | 3.94 |
1 roll2 | 515-2100-12-03 | 24 gauge wire (black) | M | 3.94 | 3.94 |
20 each | 42-2421 | miniplug with clips (need 2) | RS | 2.39 | 47.80 |
1 Note: TMS is The Magnet Store, call 1-800-222-7846 | |||||
2 Note: This is enough wire for 20 setups | |||||
4) Reflection Photophone | |||||
10 each | balloons | local | |||
10 each | 2” length of 3”-diam PVC pipe | local | |||
10 each | l” square of mirror film | local | |||
1 each3 | 2’ x 4’ x 1/8” clear plastic (cut into 4” x 8” pieces) | local or pp | 10.00 | ||
3 Note: This is enough Plexiglas for 144 setups. See PP on page 1-12 for source of pre-cut and drilled plates. | |||||
Quantity | Catalog Number | Description | Source | Unit Cost | Total Cost |
5) Photophone | |||||
10 each | 31VC205 | 500-W linear pot | M | 0.85 | 8.50 |
40 each | TE1447-57 | alligator clip (need 4) | EDL | 0.52 | 20.80 |
3 pks. | 274-415 | control knob | RS | 1.69 | 5.17 |
10 each | 12BC144 | battery snap | M | 0.30 | 3.00 |
10 each | 534-079 | battery holder | M | 0.20 | 2.00 |
10 each | 9-V battery (for photophone) | local | 0.60 | 6.00 | |
10 each | 271-1313 | 220-W resistor | RS | 0.10 | 1.00 |
40 each | 517-SJ-5514BK | rubber bumper (need 4) | M | 0.38 | 15.20 |
20 each | 11-554 | 2-56 screw | EDL | 0.037 | 0.74 |
20 each | 11-100 | 2-56 nut | EDL | 0.019 | 0.38 |
10 each | 35LS026 | 2V, 60 mA grain of wheat lamp | M | 0.37 | 3.70 |
10 each | 276-087 | 2000 med LED | RS | 1.79 | 17.90 |
1 each | 515-1356-12-90 | 24 gauge speaker wire | M | 6.30 | 6.30 |
6) Transmitter | |||||
10 each | ITT-7555-101 | telephone microphone | G | 2.01 | 20.10 |
10 each | 12-202 | AM radio | RS | 6.26 | 62.60 |
20 each | 1.5-V AA battery (need 2) | local | 1.50 | 30.00 | |
7) Optical Fiber | |||||
10 each4 | C2539 | 4’ length of optical fiber | E | 8.40 | 84.00 |
4 Note: For workshops with over 25 teachers, you should consider buying the 200 foot roll and selling the extra at cost. | |||||
8) Miscellaneous | |||||
Small and large sellable plastic bags for pre-packing components, candles, matches, clay, 2-liter bottle, and non-dairy creamer (to show light path in water). |
Quantity | Catalog Number | Description | Source | Unit Cost | Total Cost |
1) Commercial Speaker | |||||
10 each | 253-4130 | 3”, 8-Ω speaker | M | 1.83 | 18.30 |
2) Homemade Speaker | |||||
10 each | 5” foam or aluminum plate | local | |||
1 roll | L3-616 | 32 gauge magnet wire | EDL | 2.95 | 2.95 |
10 each | CB-60 | block magnet | TMS1 | 0.90 | 9.00 |
OR | |||||
10 each | 78293C | block magnet | CENCO | 4.95 | 49.50 |
3) Lightwave Receiver | |||||
10 each | 39810 | solar cell | E | 4.35 | 43.50 |
10 each | 277-1008 | miniamp (amplifier/ speaker) | RS | 10.76 | 107.60 |
10 each | 9-V battery (for miniamp) | local | 0.60 | 6.00 | |
10 each | 9-V battery (for miniamp) | local | 0.60 | 6.00 | |
1 roll2 | 515-2100-12-01 | 24 gauge wire (red) | M | 3.94 | 3.94 |
1 roll2 | 515-2100-12-03 | 24 gauge wire (black) | M | 3.94 | 3.94 |
20 each | 42-2421 | miniplug with clips (need 2) | RS | 2.39 | 47.80 |
1 Note: TMS is The Magnet Store, call 1-800-222-7846 | |||||
2 Note: This is enough wire for 20 setups | |||||
4) Reflection Photophone | |||||
10 each | balloons | local | |||
10 each | 2” length of 3”-diam PVC pipe | local | |||
10 each | l” square of mirror film | local | |||
1 each3 | 2’ x 4’ x 1/8” clear plastic (cut into 4” x 8” pieces) | local or pp | 10.00 | ||
3 Note: This is enough Plexiglas for 144 setups. See PP on page 1-12 for source of pre-cut and drilled plates. | |||||
Quantity | Catalog Number | Description | Source | Unit Cost | Total Cost |
5) Photophone | |||||
10 each | 31VC205 | 500-W linear pot | M | 0.85 | 8.50 |
40 each | TE1447-57 | alligator clip (need 4) | EDL | 0.52 | 20.80 |
3 pks. | 274-415 | control knob | RS | 1.69 | 5.17 |
10 each | 12BC144 | battery snap | M | 0.30 | 3.00 |
10 each | 534-079 | battery holder | M | 0.20 | 2.00 |
10 each | 9-V battery (for photophone) | local | 0.60 | 6.00 | |
10 each | 271-1313 | 220-W resistor | RS | 0.10 | 1.00 |
40 each | 517-SJ-5514BK | rubber bumper (need 4) | M | 0.38 | 15.20 |
20 each | 11-554 | 2-56 screw | EDL | 0.037 | 0.74 |
20 each | 11-100 | 2-56 nut | EDL | 0.019 | 0.38 |
10 each | 35LS026 | 2V, 60 mA grain of wheat lamp | M | 0.37 | 3.70 |
10 each | 276-087 | 2000 med LED | RS | 1.79 | 17.90 |
1 each | 515-1356-12-90 | 24 gauge speaker wire | M | 6.30 | 6.30 |
6) Transmitter | |||||
10 each | ITT-7555-101 | telephone microphone | G | 2.01 | 20.10 |
10 each | 12-202 | AM radio | RS | 6.26 | 62.60 |
20 each | 1.5-V AA battery (need 2) | local | 1.50 | 30.00 | |
7) Optical Fiber | |||||
10 each4 | C2539 | 4’ length of optical fiber | E | 8.40 | 84.00 |
4 Note: For workshops with over 25 teachers, you should consider buying the 200 foot roll and selling the extra at cost. | |||||
8) Miscellaneous | |||||
Small and large sellable plastic bags for pre-packing components, candles, matches, clay, 2-liter bottle, and non-dairy creamer (to show light path in water). |
To build all of the equipment and show all of the demonstrations, you should have the following equipment and tools:
laser, overhead projector, slide projector, oscilloscope, multimeter, TV remote control unit, audio oscillator (10 Hz - 10 kHz), radio-frequency (RF) generator, and microwave generator with receiver.
For each 10 participants, you should also have
1 roll of duct tape, 2 soldering irons with solder, sandpaper, 2 hot-melt glue guns with glue sticks, 2 small standard screwdrivers, 2 Phillips screwdrivers, 2 pliers, 2 wire strippers, 1 flashlight, sandpaper, clay, matches, dry cream, 2-liter soda bottle.
Suppliers:
RS = Radio Shack | PP = Precision Plastics | E = Edmund Scientific |
EDL = Edlie | M = Mouser Electronics | G = Graybar Electric |
RS = Radio Shack | PP = Precision Plastics | E = Edmund Scientific |
EDL = Edlie | M = Mouser Electronics | G = Graybar Electric |
Precision Plastics 400 Comstock Ave., Suite 4 Winter Park, FL 32789 (407) 644-2991 | Edmund Scientific 101 E. Glouster Pike Barrington, NJ 08007-1380 (609) 573-6270 | Mouser Electronics 2401 Highway 287 North Mansfield, TX 76063-4827 (800) 346-6873 |
Edlie Electronics 2700 Hempstead Pike Levittown LI, NY 11756-1443 (800) 645-4722 | Graybar Electric 2325 Featherstone Auburn Hills, MI 48326 (313) 373-3100 | The Magnet Store 6073 N.W. 167th Street Miami, FL 33015 (800) 222-7846 |
Precision Plastics 400 Comstock Ave., Suite 4 Winter Park, FL 32789 (407) 644-2991 | Edmund Scientific 101 E. Glouster Pike Barrington, NJ 08007-1380 (609) 573-6270 | Mouser Electronics 2401 Highway 287 North Mansfield, TX 76063-4827 (800) 346-6873 |
Edlie Electronics 2700 Hempstead Pike Levittown LI, NY 11756-1443 (800) 645-4722 | Graybar Electric 2325 Featherstone Auburn Hills, MI 48326 (313) 373-3100 | The Magnet Store 6073 N.W. 167th Street Miami, FL 33015 (800) 222-7846 |