LASER Transmitter/Receiver

 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.

Parts: 

C1, C2 0.1uf Ceramic Disc Capacitor 

C3 100uf 25V Electrolytic Capacitor 

R1 100K Ohm 1/4W Resistor 

R2 1M Ohm 1/4W Resistor 

R3 10K Pot 

Q1 NPN Phototransistor 

U1 741 Op Amp 

U2 LM386 Audio Amp 

SPKR1 8 Ohm Speaker 

T1 8 Ohm:2K Audio Transformer 

MISC Wire, Board, Knob For R3, LASER Tube and Power Supply 

Notes: 

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.