Here are some basic laser transmitter/receiver designs that are easy to build using a laser pen. The distance achieved relies greatly on the ability to stablize the platform that you place the transmitter on. The ability to vary the platform by fractions of a degree is the most difficult part.
Pulse Modulated Laser Transmitter & Receiver Earn 100 points for your club on Field Day using this transmitter/receiver design. Qualifies as a "UNIQUE" form of communicatons under the ARRL Field Day Rules. You can easily work this setup over several miles without too much trouble.
LM1458 (dual 741 OpAmp) modification
TL082 (dual JFET OpAmp) and PIN Diode Receiver
Kits: "Laser Beam Communicator" This is a complete
transceiver kit consisting
of two circuit boards using a standard pen-laser diode (included in kit) to transmit voice. Uses Pulse-width modulation at 20kHz, built-in AGC. Receiver uses a photo transistor for laser detection.
Excellent kit with all parts including well written instructions. More sophisticated than expected and the price of $39.95 is well worth it.
"Cheepo Laser CW Transceiver" by Jim Moss. This is a "KISS" (Keep It Simple Stupid) project with a 555 Timer chip used to produce an 800Hz tone that is "keyed" to send morse code. The receiver is extremely sensitive and yet very simple to build. All parts available at Radio Shack. Depending on your mounting apparatus and aiming skills, this transceiver can easily transmit/receive over many miles.
Check out WB9AJZ's Laser Web Page for more articles on circuit boards, laser mounting, aiming, lenses, etc.
K3PGP FET/PIN Diode Receiver (very sensitive--40miles)
John Yurek-K3PGP has developed a very simple high gain receiver using an MPF-102 FET and a PIN Diode and some special techniques he has gained from years of experience. His web site has all the pictures you'll need to see how he has constructed his receiver (point-to-point construction) and the very practical mounting/shielding system he uses to get reliable results.
Check out the February 2000 issue of CQ magainze (pg. 11) for a detailed article on building a MCW transmitter and John-K3PGP's receiver to achieve a 40 mile QSO from Glasgow, Scotland. This article features a couple of close-up views of laser mounting schemes using threaded rods and small transducers (speakers) to make very fine pointing adjustments.
Pictures of 2001 Field Day Laser Contacts
Other web sites of interest
Interactive Physics Lesson on Why and How Lasers Work . . . . Very Cool !!
|More Laser Sites . . .