Laser Communication Circuit We can provide wireless audio communication with the laser communication circuit described below. In fact, if a parabolic reflector is used, this distance can easily be a few kilometers, and even at this distance the sound transmission will be very clear.
Lazy receiver and transmitter circuits. At 5 miliWat power, we used a kind of laser diode that emits a beam of 650 nm wavelength, which we use in our laser pointers.
The receiving circuit and the transmitting circuit are fed separately with a 9 volt battery. The emitter circuit collects electret microphone sounds and emits a laser diode. The receiver uses a 4-36 ohm speaker and contains an amplifier. To operate the system, the laser receiver and transmitter must be able to see each other as usual. It is very difficult to intervene and listen to someone else in this system. Also, an infrared (IR) laser diode can be used if desired, and no one can see the beam.
LAZY SOUND TRANSMITTER SCHEMATIC
The laser current is set by VR1.
LAZY RECEIVER DYNAMICS CHART
Lazy sound Transmitter Description: The operating value of the laser diode (5mW 650 NM) is usually 30mA. The laser is operated between 1-40mA. The laser diode current decays when it exceeds 80mA. The metal sheath is removed as it will cause damage in excess temperature. The circuit uses 68 ohm NTC for temperature protection. In this way, the working life of the laser diode is 20.00 hours.
Parts Placement Plan of the Transmitter and Transmitter of the Transmitter. The red LED used in the transmitter is vibrating harmoniously when the sound signals are received.
Receiver Description: The signal sent by the transmitter is received by the photodiode in the receiver. The visible light should be a photodiode that is used in this circuit. The receiver uses the LM386 amplifier. It is driven by a speaker with a small resistance of four ohms and pulling 350 mW of 9 volts from the coil.
Buyer Dynamics Part Placement Plan
The photodiode is mounted directly on the receiver plate. Carefully solder the laser diode because it may deteriorate from excessive heat. It can be done by taking cooling measures.
First open the transmitter and bring VR1 to the half position. Turn it clockwise. Slowly turn it clockwise to increase the current and see the light of the laser diode. You also need to flicker on the LED when you click on the microphone. Here the laser beam does not shake.
The receiver and transmitter are placed at a distance of 1 meter. When the receiver is turned on, the loudness of the loudspeaker is visible, and if necessary, a piece of paper can be placed in front of the photodiode to prevent excessive noise. This paper should not be used in normal use because the distance will increase. In this way the output of the microphone is controlled by the speaker output.
Laser Sound Printing Circuit
Emitting Material List
Resistances
R1 4.7k
R2,3 1 00k
R4 68k
R5 10k
R6 4.7M
R7 220k
R8-1 0 220 ohm
Rl 1.12 47k
R13 56 ohm 1 / 2W
R14 68 ohm NTC thermistor
VR1 1 00k trimpot
Capacitors
Cl, 2 1OuF 16V
C3 4.7uF 16V electrolytic
C4,5 10OuF 16V electrolytic
C6,7,9 68nF
C8,1 0 0.47uF without polarity
Semiconductors
LED1 5mm green LED
Laser 5mW / 65Onm laser diode
Ql, 2 BC557 PNP
03 2N5484 N-ch JFET
Dl-7 1N4148 signal diode
D8,9 1 N60 germanium diode
lci 7805 5V regulator
1C2 LM358 op-amp
PCB 65mm x 36mm
8-pin IC socket; 9V battery and battery clip.
Receiving Material List
Resistors
Rl 680 ohm
R2 22 ohm
R3 4.7k
R4 39k
R5 3.gk
R6 10k
R7 1k
R8 220 ohm
Rg 4.7 ohm
VR1 50k trimpot
Capacitors
Cl, 2,5,7 10OuF 16V electrolytic
C3,4 1 uF 16V electrolytic
C6 15nF polyester
Qi BC549 NPN
LM386
ZD1 5.6V 40OmW zener
PCB 36mm x 64m
Photo diode
9V battery
Speaker
8 pin integrated socket
