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sending high frequency in phone line

Hello,

I have an indicator (LED) (in some interfacing box) which is located

50 meters from my board. Telephone signal is transmitted from My board to Interfacing box through CAT-5 cable.

I get a Command from my processor to glow the LED. Can i superimposing it with the telephone signal in the form of high frequency signal (10 KHz)(which is generated on Processor LED glow command) through the line which is decoded in the interfacing box, which in turn glows the LED?

Or Is there any other good and cheap method of glowing the LED.

Thank you Regards Praveen

Reply to
praveen
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You can use any "out of band" signal to operate that LED. All you need, is the appropriate filtering to keep any audible signal out of the phone and also interfering voice energy out of your device. In fact, it would probably be best, select a frequency well above hearing range, to avoid interference in either direction. Sub-audible frequencies could also work. Then again, if you've got some spare pairs, why not use them?

Reply to
James Knott

I'd use polarity inversion if I only had one pair to play with, but if you've got Cat5, you've got four pairs, and you only need one for the phone line....

Reply to
William P.N. Smith

Hello William, Yes i am using CAT-5 but i donot have spare line. I have ethernet data (4 line) and 2 phone line (4 line) used in CAT-5. Tell me how will you reverse the line?

Thanks and regards Praveen

Reply to
praveen

For example with 4 transistors bridge connected ...

Reply to
Stanislaw Chmielarz

If it's a real live actual phone line from the telco I'd probably use a DPDT relay. (Most modern) Telephones are polarity insensitive, and the handset current can probably even run the LED for you, just put it in series with the phone line, and add a reverse diode to conduct when you have the polarity inverted.

Reply to
William P.N. Smith

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