UK Vintage Radio Repair and Restoration Discussion Forum

UK Vintage Radio Repair and Restoration Discussion Forum (
-   Vintage Telephony and Telecomms (
-   -   CB935 switchboard queries (

geofflove 16th Feb 2021 12:20 am

CB935 switchboard queries
Hi, I'm just about to take delivery of a CB935 2 + 4 switchboard.

I won't be using it as a switchboard (I don't know it is is fully working anyway). However, I would like to utilise some of the indicators etc in it in some way so need a little info please.

I understand the board works on a 12v dc supply. I also know it has a generator to provide a ring to other lines. I'm guessing the generator is around 50v ac?

In terms of the dolls eyes indicators what voltage do these run on? Are they powered by the 12v or 50v line? Do these indicators have 2 or 3 positions?

Does the board have it's own buzzer or bell to sound or did it use an external bell?


Dave Moll 16th Feb 2021 10:03 am

Re: CB935 switchboard queries
The dolls' eyes (for the extensions) are operated from the 12V DC by detecting a loop when the extension goes off-hook (or goes back on-hook when the line is selected). The drop-down indicators for the exchange lines are operated by the incoming ringing current.

When a doll's eye operates it closes a contact to operate an internal buzzer.

geofflove 16th Feb 2021 10:25 am

Re: CB935 switchboard queries
Thanks - that's really helpful. Cheers

All times are GMT. The time now is 4:18 am.

Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.