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The laser transceiver is a free space optical communication device that encodes audio on a laser beam using pulse width modulation (PWM). A single transmitter and receiver unit can be built for about $15-$20 in parts. We used to use this for a demonstration in ELEC 3030 (RF Systems Lab), but aligning the lasers took quite a bit of time to setup.
This uses a laser pointer communicator designed by Ron Jones (K7RJ). We made no changes to it other than adding an on/off switch.
Here's a list of the stuff you'll need to buy to build one. It runs off two 9V batteries, so you'll need to buy parts that are rated above 9V. Stuff in the 15V-20V range is good, but if you can find stuff for cheap that's rated higher than thats fine. The diodes we used were rated to 100V and the electrolytic capacitor was rated to 35V.
Buying extra parts is always a good idea, and due to price breaks and quantity discounts, sometimes an item will cost the same (or, rarely, less!) if you buy 10 instead of 8.
You can find the item by searching for the manufacturer part number. You don't have to by the one we used, but they are the ones we used in our transmitter. Where we haven't listed a part number (like resistors, switches, or battery clips), any will do.
|Item||Quantity||Manufacturer Part Number|
|photo diode sensitive to 650nm||1||SFH 229|
|100k ohm resistor||1|
|0.01 uF ceramic capacitor||1|
|0.1 uF ceramic capacitor||2|
|10 uF electrolytic capacitor||2|
|3.5mm audio jack||2||ACJS-MV35-3|
|0.001 uF ceramic capacitor||1|
|100k ohm resistor||2|
|15k ohm resistor||4|
|240 ohm resistor||1|
|4V zener diode||1||TZX3V9C-TAP|
|555 timer rated to at least 15V||1||NE555N|
|10k ohm potentiomter||1|
|9V battery clip||2|