Build DIY Audio infrared transmitter???

[thomgun_lc]

How to send an audio signal from microphone to loudspeaker without cable but using infrared??

 

[IanP]

Check out this site:
"Basic Infra Red Link For Audio Communication"
**broken link removed**

Regards,
IanP

 

[thomgun_lc]

WOw, that's cool, i will try that devices. I will build two pair for full duplex communication

 

[the_risk_master]

Hi,

Sir How long does a typical IR Transmitter can cover, Im planning to set up a link between two PCs about 250-300 meters away, is this possible?

 

[hassenman]

hi the_risk_master ,
well the typical ir transmitter range is about 10 meter (max) .
the typical ir transmitter will operate at a low frequency , so your connection will be very slow .
and u should know that ir beams will not bybass obstacles (like walls etc...) , and saying this cause i can't imagine 300 m with no obstacles unless you're planning to set up your connection in the desert .
u can use RF connection instead .

 

[Beowolf]

the_risk_master, I thik that it can be done, but by replacing the IR Leds with a laser diodes and some lenses.... But, as hassenman noted, it would be easier to use rf communication..

 

[thomgun_lc]

Hi there, i try to build this Infrared Audio transmitter.I try to build the infrared audio transmitter first. The schematic with description is in **broken link removed** try to build the transmitter and connect it with my PDA which generates sound. I try to observe the infrared (using digital camera because human eyes can't see IR light), and the infra red are blinking based on audio source. (it's work)The trouble, come in the receiver. I have build the same receiver which in the web, but it doesn't make a sound, what's wrong.
I try to use two reciever component, like Photodiode and Phototransistor, but the result is same, it doesn't work.

 

[Beowolf]

Try to measure volts on the output.. Is there any?

It is possible that the receiver is too sensitive, so it saturates from ambient light. Try finding a IR photodiode matching the wavelength of the diode U used in the transmitter.

 

[the_risk_master]

Hi Sir Beowolf,

Thanks for your reply (also Hassenman), so if Im going to link two PCs 250-300m away what type of RF comm technique should I imply without using microwave?

Thanks in advance

 

[Beowolf]

It depends on speed you want to achieve and the type of connection you want. I suppose you want to form an network (via TCP/IP).

The thing is... if you want to practice with RF connection, U can build some DIY rf tranciever ( currently I'm thinking of using rfPICs).
But if you intend to use it seriously try with standard WiFi equipment. In my country PCI WiFi card costs around 25-30?, and for that range you can use home-made antennas.

Building will last a least 1 month if you know how to program a PIC, and it will cost you half the price of the WiFi, but it's speed will be 100 times less.

 

[the_risk_master]

Oooh, Thank you.

 

[thomgun_lc]

I tried to build the IR audio transmitter, which is in www.i-hacked.com/content/view/30/58/.It's worked. I do some changes, but it still have a lot noise than the transmitted sound. It's awfull.
I read some article, and they suggest to modulate the sound, using opamp modulate the sound with triangle wave, so can produce pwm signal. After transmit, using low pass filter to demodulate, but how to do that?Does anyone know the simple triangle wave using opamp?

 

[Beowolf]

Google using: Class D amp

You can try this one:

 

[thomgun_lc]

Thx i will try to build that so i can modulate the sound to avoid noise

 

[Beowolf]

I forgot, on the reciving end use schmidtt triggered logic(74hc14) to eliminate noise and to get an clear signal, then run it through a LPF.