Leich 911 wired to 901

[stub]

How would you hook these up for a ringing intercom?  stub

left click on pic to enlarge

[Phonesrfun]

I would use separate batteries, although for just an intercom, a single battery would probably work. 

Tip (Terminal 1) of each phone to each other. Ring (Terminal 2) of each phone to each other.


Batteries between terminals 2 and 4 on each phone. Alternatively, I would think that by wiring terminals 4 of each phone to each other and having a single battery between the common terminals 2 and 4 would probably work.  My guess by looking at the diagram.  I don't have any of these to try it out with.

[dsk]

As Bill says tip to tip, and ring to ring, and separate batteries, 3-4.5 Volts.  This is a safe solution. 
Using a common battery for talking may disturb the anti sidetone system slightly, but not as much as you will hear it. 

A little googeling gets this page among others, the intercom her has 12 telephones in parallel, and they use common batteries in each building.
http://www.valhallatreefarm.com/magneto%20phone/phonemagneto.htm

What i dislike her is to use such high voltage as car batteries, it may kill some transmitter capsules,  and it might definitely be a risk fire.  Try to short a car battery with a phone wire, please do it outdoors, and use protective glasses and cloths.  Then imagine if the wire you just burned was clamped to a wood wall.  In worst case the battery may explode.

dsk

[dsk]

If you do not want the telephone you call from, to ring when you call, only when the other party calls you, move the wire from the ringer from terminal 10 to terminal 13.

dsk

[unbeldi]

How would you hook these up for a ringing intercom?  stub

left click on pic to enlarge

The two schematics in your page show different hook switch wiring for the two instruments.  I think this must be wrong. The only difference from a 901 to a 911 is the added mechanical two-step latch that prevents the transmitter circuit from closing when the set goes off-hook.   This is entirely mechanical and the four-contact hook switch is otherwise wired identically in the two model types.

As a party line simply wire them in parallel.  Depending on the manner in which the ringer and generator were previously wired, you either need to use a ground between them, if grounded ringing, or if they are wired for metallic ringing, then only tip and ring are needed.

As a typical intercom with only one common battery, they could be converted to common battery mode, this is a design option.  In that case you have to decide on ringing arrangements, but if you are simply using a battery in series without any AC chokes, then it seems it would be ok to let them keep the generator for ringing, as the AC would simply travel through the battery.  The internal resistance of a battery is only perhaps 1 ohm.

PS: Looking at the GSP, it does show that the two switches are swapped in the 901 and 911, so that the proper circuit closes first, rather than last. Sorry... text corrected.  The diagrams appear to come from that GSP, but the way they drew that is still wrong.

[dsk]

I would have done it like this. (twisted wire) and probably have moved the ringer wire if it is long enough.

dsk

[stub]

Thanks Bill , dsk , unbeldi .  stub