CORDLESS PHONES FOR INTERCOM SYSTEM?

IF YOU TAKE 2 BASE UNITS, MUST BE BASE UNITS CORDLESS PHONES THAT ARE ON THE SAME FREQ. AND JUST RUN THE PHONE WIRE BETWEEN THEM. NOT TO ANY WALL PHONE COMPANY SOURCE BUT JUST BETWEEN THE 2 BASE UNITS. WILL THIS WORK AS A HANDY WIRELESS INTERCOM SYSTEM? THE RANGE SHOULD BE GREAT I WOULD THINK....HAS ANYONE DONE THIS OR TRIED THIS...LET ME KNOW

jduffy544 years ago
ALSO, YOU COULD JUST SET UP TWO MICROPHONES HOOKED UP TO SPEAKERS THROUGH A PREAMP AND POWER AMPLIFIER, AS WELL AS AN AUDIO FREQUENCY OSCILLATOR ATTACHED BEFORE THE POWER AMP TO RING THE OTHER END. BY PASSING THE SIGNAL ALONG THE LINE AFTER THE PREAMP BUT BEFORE THE MAIN AMP, YOU SHOULD GET A VERY LONG TRANSMISSION DISTANCE. IT SHOULD ALSO BE POSSIBLE TO SUPPLY POWER, GROUND AND BOTH SIGNALS THROUGH A STANDARD PHONE WIRE, ASSUMING ITS NOT CONNECTED TO THE "REAL" PHONE LINE.
It seems like I've answered this question before:
https://www.instructables.com/answers/Pls-let-me-know-the-cheapest-way-to-make-an-interc/

And someone else has written an instructable on how to do this:
https://www.instructables.com/id/Build-your-own-intercom-or-walkie-talkie-out-of-tw/

POTS (plail 'ol telephone service) phones are designed to be powered by the phone line, so the line you connect between your two phones must be powered. I forget what the actual spec is, but something in the range of 6 to 12 volts with an output impedance of around 50 ohms, or less, will work.  I think the instructable I linked to used a 9V battery.
2phones.png
The tricky part is getting either of the phones to ring. This requires a "ring signal".
orksecurity7 years ago
It isn't quite that simple, but it is possible to set up a local loop that telephone instruments can connect to. I don't remember the exact details, but a websearch will probably find them; I think it's basically a matter of providing power.

If you want the phones to be able to cause each other to ring, that's a lot more complicated.

Note that some wireless phones already have an intercom built into them, if you configure several handsets to talk to the same base. If you do that, you probably don't need to provide the phone line.

Range... Depends on the phone. The ones I use will cover my whole house if I put the base unit in the center of the house, but if I put it in one corner they can't quite reach the other corner through the various walls and what not. They will reach much, but not all of, my yard. They definitely won't go farther than that.