Laser Communication Project Circuit Schematic using LASER Diode and LM386 Low Voltage Audio Amplifier

Here is a wireless LASER communication project for you using LM386 low voltage audio power amplifier circuit. The LM386 is a power amplifier (audio amp chip) IC designed for use in low voltage customer applications. The inside gain is set to 20, but adding of an external resistor and capacitor between pins 1 and 8 will enlarge the gain to any value from 20 to 200. The inputs are ground referenced while the output automatically biases to one half of the supply voltage. The quiescent power drain is only 36 milli watts when operating from a 9 volt supply. Below laser communicator transmitter and receiver schematics are described in detail. Hope this project shows you the importance of laser in communication.

Circuit Diagram of LASER communication transmitter

laser communication transmitter

Wireless LASER communication receiver

Laser communication reciever

Components required

  1. LM386 IC x 2 
  2. Potentio meters (VR1=10k Ω, VR4=10k Ω) 
  3. Presets (VR2=220 Ω) 
  4. Resistors (10Ω x 2, 56 Ω x 2) 
  5. Capacitors (100µF-25V, 10µF-25V x 5, 0.047µF x 2, 220µF-25V) 
  6. Calculator’s solar panel 
  7. Laser diode 
  8. Speaker (8 Ω, 0.5W)

Working LASER communication transmitter

  • This laser communication system transmits sounds though a laser beam. The intensity of laser beam changes with the amplitude of sound signal. 
  • The variation in LASER beam intensity is converted to variation in voltage level by using a calculator’s solar panel. 
Calculator solar panel

solar panel
  • The voltage variation in solar panel is amplified by a low voltage audio power amplifier LM386 and reproduced by speaker. 
  • The maximum output of this audio amplifier is 1 watt, while its voltage gain is 20 to 200. 
  • Here a laser diode with maximum operating voltage of 2.6 volts and maximum operating current of 45 mA is used to transmit the audio signal. 
  • The voltage divider formed by R2, R3, VR3 keeps the voltage as well as the current for the laser diode. Potentiometer VR1 is used to change the level of the input audio signal. You can apply the input audio signal from mic, CD player or any other device. 
  • Capacitor C2 and preset VR2 are used to vary the gain of the amplifier IC.

Working LASER communication receiver

  • The transmitted light is received by calculator’s solar panel and amplified by the LM386 IC.
  • The gain of the amplifier is fixed by capacitor C7. 
  • Preset VR4 is used to change the signal level from solar panel. 
  • C5 acts as coupling capacitor, it removes the DC voltages from the solar panel. 
  • The output is fed to speaker via another coupling capacitor C8.

Pin out of LM386 and other components

LM386
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