This set of two circuits from the basis for a very simple light wave transmitter. A LASER beam is modulated and then aimed at a receiver that demodulates the signal and then presents the information (voice, data, etc..). The whole thing is very easy to build and requires no specialized parts execpt for the LASER itself. LASERs are available from MWK Industries.
Schematic Of Transmitter
Schematic Of Receiver
0.1uf Ceramic Disc Capacitor
100uf 25V Electrolytic Capacitor
100K Ohm 1/4W Resistor
1M Ohm 1/4W Resistor
741 Op Amp
LM386 Audio Amp
8 Ohm Speaker
8 Ohm:2K Audio Transformer
Wire, Board, Knob For R3, LASER Tube and Power Supply
1. In the transmitter schematic, no ballast resistor is shown because most small LASER power supplies already have one built in. Yours may differ, and a resistor may be needed.
2. The receiver should be kept away from bright lights. You may want to put a piece of wax paper in front of Q1 to keep the LASER from swamping it.
3. In order to get any decent amount of modulation, you may need to drive T1 with more then a watt.
4. The circuit can be made to transmit computer data with the use of two modem chips.
Source: Electronics Lab