Victrolaman I am looking for a circuit schematic to share with you but have found no real info yet.
It looks a lot like a conneticut duplex telephone
http://tinyurl.com/6wusetn It appears that you have the following:
Microphone(transmitter)
Earpiece(receiver)
Low voltage bell (a buzzer with a bell hammer)
A normally open pushbutton.
a hook switch
Is there a coil (transformer) ?
Is there a capacitor (can with 2 or more wires)?
is the button connected to one wire and when pushed connected to a different wire?
How many wires does it appear to have had connecting it to the other station? 2 or 4 or more?
one way intercoms can be wired is:
station 1 battery to station 1 Transmitter to station 2 Receiver
station 2 battery to station 2 transmitter to station 1 Receiver
This circut has the problem of degrading the magnetism in the earpiece over time and using more wires so is generally not preferred.
A more usual and preffered way of doing it is to use a coil (transformer)
Station 1 battery to station 1 Transmitter to coil primary then back to battery / Coil secondary to station 2 receiver
Station 2 battery to station 2 Transmitter to coil primary then back to battery / Coil secondary to station 1 receiver
Battery would be 3 volts dc. The bell should ring on 3volts dc, perhaps 6 or 12v
OR it could be wired like a telephone with everything in series, which is the best circuit as it only needs two wires.
Just musing, cant speak definitively on the subject.