Light Fidelity or Li-Fi is a Visible Light Communications (VLC) system running wireless communications travelling at very high speeds. Here, we describe the design of a Li-Fi dongle (transmitter) and speaker (receiver) for audio and music applications. The proposed system is a replacement for wired speakers that plays audio signals received through light.
The proposed Li-Fi dongle is connected to the audio jack output available on mobile phones. It has an LED through which audio/music signals are transmitted as light signals. These light signals are captured by the Li-Fi speaker through the solar cell array.
PARTS LIST :
T1, T2, T3 – BC337 npn transistors
LED1 – White LED 1W
Resistors (all 1/4-watt, ±5% carbon):
R1, R3, R5 – 4.7K ohm
R2, R4, R6, R8, R9, R10 – 1K ohm
R7 – 2.2E ohm(1W)
C1, C2, C3 – 2.2uF
CON1 – 3.5mm Audio Jack(Male)
BATT1 – 9V Battery
3V, 200mA Solar Panel
Speaker with inbuilt amplifier
Audio Source(MP3 player, mobile phone)
Let us begin :
- Connect the +ve terminal of BATT1 to a Red Wire and the -ve terminal to a Black Wire. Connect one of CON1’s terminals to the Black Wire.
- Connect R1 to the Red Wire. Connect R2, R8, C1’s -ve terminal to R1’s other terminal in parallel. C1’s other terminal is connected to CON1’s other terminal, the one not connected to the Black Wire. R2’s other terminal is connected to the Black Wire. R8’s other terminal to T1’s Base.
- Repeat the same with R3, R4, R9, C2, T2 and R5, R6, R10, C3, T3.
- Connect R7 to the Red Wire and its other terminal to LED1’s +ve terminal. Connect T1, T2, T3’s Collector terminals in parallel to LED1’s -ve terminal.
- Connect T1, T2, T3’s Emitter terminals to the Black Wire.
- The Li-Fi speaker is designed by connecting the output of a 3V, 200mA solar cell array to a speaker’s audio input. For this, connect the terminals of the solar panel to a 3.5mm female audio socket. Then, connect the 3.5mm audio jack from the speaker to the female socket. You can use any speaker with an inbuilt amplifier.
After adjusting the band equaliser in the audio source and the distance between the solar panel and the light source, you can get almost noise-free sound from the speaker.
The maximum distance/range between the transmitter and receiver depends on the number of amplifier stages. For a three-stage CE amplifier, the maximum distance is about two metres with LED illuminance of 13,842.00 lux at the receiver side. For a five-stage CE amplifier, the distance can be up to 2.6 metres with LED illuminance of 17,382.00 lux. It was observed that as you increase the number of CE amplifier stages connected in parallel in the transmitter circuit, the intensity of LED light also increases, which, in turn, increases the maximum distance up to which the sound is audible from the Li-Fi speaker.
The original product can be found here.