UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Plugging in extension causes main to ring

Station X · 25th Feb 2021, 1:40 pm

I know that extension wiring faults can cause this, but I've only ever known it happen with phones that have electronic tone ringers rather than electro-magnetic bells. The latter require 25Hz AC to operate them and as far as I know this will only be present when an incoming call is awaiting answer.

25th Feb 2021, 1:40 pm	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Plugging in extension causes main to ring I know that extension wiring faults can cause this, but I've only ever known it happen with phones that have electronic tone ringers rather than electro-magnetic bells. The latter require 25Hz AC to operate them and as far as I know this will only be present when an incoming call is awaiting answer. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.