Laser Communication (Transmitter – Receiver)

This is the circuit diagram of laser communication system that transmit the sound or music signals by way of a laser beam. The intensity of the laser beam varies together with the amplitude of the sound signal. The variation within the intensity of the laser beam is converted into a variation in the voltage level by utilizing a calculator”s solar panel. The voltage variation on the solar panel is amplified by a low-voltage audio power amplifier LM386 and reproduced by a speaker. The maximum output of audio amplifier LM386 is 1W, whilst its voltage achieve is 20 to 200.

The circuit module consists of a transmitter and also a receiver. Either the transmitter as well as the receiver are assembled around IC LM386, it is powered by a 9V battery. Take a note that this circuit is different with AV transmitter and AV receiver which can be used for sound and video communication, this laser communication circuit only work for audio/sound transmission.

Laser Transmitter Circuit
Here the circuit diagram of laser transmitter

A laser diode (LD1) with maximum operating voltage of about 2.6V DC and maximum operating current of 45 mA is applied to transmit the audio signal. The voltage divider network formed by R2, R3 and VR3 keeps the voltage and also the current for the laser diode in the secured spot.

In place of the laser diode, it is possible to also use a laser pointer. Take out the battery from the laser pointer. Extend two wires from terminals of LD1 and connect them towards the battery terminals of laser pointer. The spring within the laser pointer will be the negative terminal. The output power of the laser pointer is 5 mW. Be careful when doing work with laser, as direct exposure to the laser beam could be hazardous to your eyes. Point the laser beam to the solar panel.

Potmeter VR1 (10-kilo-ohm) is applied to adjust the level of the input audio signal. The audio input (Vin) is taken from the preamplifier output of the music system (CD player, DVD player, etc). Capacitor C2 and preset VR2 are applied to vary the gain of the LM386.

Laser Receiver Circuit
Here the circuit diagram of laser receiver:

The audio signal transmitted by the laser diode (LD1) is received by the calculator”s solar panel and amplified by IC2. The gain of the amplifier is fixed by capacitor C7. Preset VR4 is utilized to adjust the signal level from the solar panel. This signal is fed to input pin 3 of IC2 via coupling capacitor C5 so that the DC value from the solar panel could be eliminated. The amplified output from IC2 is fed towards the speaker, which plays the music from the CD player linked on the input (Vin) of IC1.

This Laser Communication (Transmitter – Receiver) is already tested and claimed to be work.

You can download the circuit in PDF document from the following link:
» Laser Communication System Circuit