What to do with a bunch of Phones (USA)?

[MikeMl]

I finally cut the cord, so I am left with a bunch (~8) of ma-Bell style house phones. The house and hangar are wired with RJ-11 jacks (Red-Green and Yellow-Black pairs) that run in the walls, so I effectively have a four wire network between dozens of RJ-11 jacks.

Is there a simple circuit I could build that sits at one of the RJ-11s, puts a dc current on the red-green pair, watches for off-hook from any distal phones, generates a ringing signal for a few seconds, to allow an intercom conversation between any two phones on the network? I dont care if all phones ring when one comes off-hook.

Alternatively, ring until second phone comes off-hook?

 

[cowboybob]

Sounds like a job for an Uno + some other stuff (or equivalent). Just found this.

Sort of a waste of computing power, but what the hey. Certainly cheap enough... .

 

[unclejed613]

there are boxes you can use, such as a VOIP box, or something like https://www.vikingelectronics.com/products/dle-300/ to provide a local source of ringing voltage and loop current. or, milsurp field phones can supply (from hand cranked alternators) ringing voltage. the loop could be powered from a battery or a suitable open frame power supply.

 

[dr pepper]

I did this for a friend, but its super simple.
You pick up, dial 000, and the pulses are applied to a choke, the bemf makes the bell ring at t'other end (there are only 2 phones).
The wires are a part of a barbed wire cattle fence, the phone is in a farm shop type thing, customers and staff can call the office with it, it works over 1/4 mile easily, power is just an old industrial 24v power supply brick.

 

[dknguyen]

I did this for a friend, but its super simple.
You pick up, dial 000, and the pulses are applied to a choke, the bemf makes the bell ring at t'other end (there are only 2 phones).
The wires are a part of a barbed wire cattle fence, the phone is in a farm shop type thing, customers and staff can call the office with it, it works over 1/4 mile easily, power is just an old industrial 24v power supply brick.

The BEMF from the dialing current is enough to do that? The dialing mechanisms on these old rotary phones are just beefy old mechanical switches that can handle a lot of current right?

 

[MikeMl]

All my phones are touch-tone, not rotary dial. I suppose I could put a tone detector in the controller which after a delay triggers a 20Hz ringing generator. To prevent loading the ringing generator, the person initiating the ring-back would have to take one phone off-hook (to allow the making of a touch-tone), then hang-up again, to allow all the phones to ring. Sounds like a job for an Arduino...

 

[dr pepper]

Yes dtmf tones might mess you up.
Theres a chip I think 8170 that detects tones & gives bcd outputs, you could use one of these and connect one of the o/p's to a relay that switches Ac onto the line to make other phones ring, 4 phones would be straightforward.

Yes the phones I used were old british Gpo 703's, there was a meaty coil inside them, I repurposed it so that when the rotary dial was moved it pulsed the coil on return back to the park position, the bemf makes a loud ring from the bell, but just one ding (10 dings for 0) so it doesnt sound right, but it works and cost nothing.