Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Optical voice transceiver over the air...

Status
Not open for further replies.
Externet

Externet

Advanced Member level 2
Joined
Jan 29, 2004
Messages
579
Helped
28
Reputation
58
Reaction score
29
Trophy points
1,308
Location
Mideast US
Activity points
5,659
Is there any links to tutorials, projects, schematics, kits... that you know of for a LED based voice intercom/transceiver over the air ? (not laser, not fiber optics)
 

Obviously you can alter led brightness directly according to the audio amplitude. (Level-shift your signal into the positive region.) However this does not give linear response.

Instead a better way is PWM or PFM. A 555 IC can create PWM output, by applying your audio signal to its 'ctl' pin.



Also try an internet search on "555 pwm led".
 

If you are wondering about carrier free communication system, please be advised that you may encounter severe noise and interference problem from all other sources. You may consider the setup commonly used by the remote controls used by many electronic instruments. You can also use AM or FM modulation (how do you plan to take care of unwanted reflections from other objects in the room).
 

Thanks.
OK. Pulse frequency modulation, pulse width modulation, amplitude modulation, frequency modulation...

-No expected reflections nor interference-

What about the receivers for them ? Any links where to learn ?
 

Here is a complete system. Falstad's simulator does not support an optosensor, therefore I put in a resistor as a middleman between the transmitter and receiver.

The capacitor low-pass filter lets through the audio.



The carrier needs to be a higher frequency than my simulation has. Therefore reduce capacitor values to suit.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top