Author Topic: Graybar Inter-Phone, possible to get working again/use as intercom phone?  (Read 801 times)

Offline JonasClark

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I have a Graybar Inter-Phone, removed from a 1936 movie theatre where I used to work. I assume there used to be three of them (probably box office, office, and projection booth) but by the time I worked there, only one still existed. Inner stamp is 2527-C-2, it's a wall-mounted type with a bell inside, and has two line pushbuttons.

I'm hooking up some phones with a ringdown device as an intercom system. Is it possible to connect this as a telephone (same set-up, pick it up and the phones at the other end ring)? With the line buttons disconnected, I'm sure.

Also, this thing really needs rewiring. I don't feel comfortable trying to do so myself, but I don't think I can afford a pro full restoration. Is there any other option to just get it into basic working order, leaving on all the paint slop and grime? I kind of like it looking old and well-loved.

unbeldi

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Interphones used a very simple circuit principle, having the transmitter and receiver in series.  The ringer was either driven by a battery or directly from electrical grid current, not like in telephones which ring at 20 Hz alternating current with a voltage of ca. 50 to 105 V.  Intercom ringers or buzzers were usually switched with a relay.
You cannot operate these from a regular telephone line, unless you design some trigger circuit with the proper electrical conditions for operating the ringing relay of the Interphone.

The 2527-C-2 was part of the Graybar Inter-Phone System No. 11.  I am going to attach some info on this system to this message.
Ok, I attached two docs with pages from Graybar catalogs of the 1930s, pertaining to the No. 11 system.
« Last Edit: August 31, 2016, 09:26:12 AM by unbeldi »

Offline JonasClark

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Fascinating stuff, thanks! I'll just hang it up for display, then.