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Old 16th Feb 2021, 10:03 am   #2
Dave Moll
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Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 5,327
Default 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.
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