Return-Path: Received: (qmail 18479 invoked from network); 8 Nov 2001 09:12:04 -0000 Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 8 Nov 2001 09:12:04 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 22886 invoked from network); 8 Nov 2001 09:11:50 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys.services.quay.plus.net with SMTP; 8 Nov 2001 09:11:50 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 161kZr-00035a-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 08 Nov 2001 08:30:23 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from bob.dera.gov.uk ([192.5.29.90]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 161kZq-00035V-00 for rsgb_lf_group@blacksheep.org; Thu, 08 Nov 2001 08:30:22 +0000 Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id IAA31479; Thu, 8 Nov 2001 08:37:50 GMT Received: (qmail 14243 invoked from network); 8 Nov 2001 09:14:34 -0000 Received: from gauntlet.mail.dstl.gov.uk (192.168.9.10) by baton.dstl.gov.uk with SMTP; 8 Nov 2001 09:14:34 -0000 Received: by gauntlet.mail.dstl.gov.uk; id IAA22461; Thu, 8 Nov 2001 08:49:47 GMT Received: from unknown(172.17.128.171) by gauntlet.mail.dstl.gov.uk via smap (3.2) id xma022458; Thu, 8 Nov 01 08:49:20 GMT Received: from FRN-MAIL-R3.dstl.gov.uk (unverified) by mailguard.dstl.gov.uk (Content Technologies SMTPRS 4.1.5) with ESMTP id for ; Thu, 8 Nov 2001 08:26:16 +0000 Received: by frn-mail-r3.dstl.gov.uk with Internet Mail Service (5.5.2650.21) id ; Thu, 8 Nov 2001 08:22:27 -0000 Message-ID: <7D653C9C42F5D411A27C00508BF8803D55C618@PDW-MAIL-R1> From: "Talbot Andrew" To: rsgb_lf_group@blacksheep.org Subject: RE: LF: Re: Ringing Voltage on Telephone , boo-boo Date: Thu, 8 Nov 2001 08:22:17 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset=iso-8859-1; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Same in the UK. Ring voltage is a low frequency bipolar spike waveform of a 100V or so amplitude, Originally designed to hit the bells firmly, the waveform seems to have been kept for legacy reasons. Modern phones rectify the AC ringing voltage, after it has been separated by a capacitor from the DC line voltage of 50V, and use this to supply the audio ringer. Ring tones are generated locally in response to the network signalling instructions and returned to the caller. Andy G4JNT > -----Original Message----- > From: WarmSpgs@aol.com [mailto:WarmSpgs@aol.com] > Sent: 2001-11-08 06:51 > To: rsgb_lf_group@blacksheep.org > Subject: Re: LF: Re: Ringing Voltage on Telephone, boo-boo > > > I don't know how it is in Canada, but in the States, the 20Hz > component is > the only ringing voltage sent across the line to the > telephone set, which can > readily be confirmed by sticking a blocking capacitor and a bridging > transformer acorss the line and looking at the result directly on an > oscilloscope. The modulated audio frequency tones are sent from the > switching office back to the caller, not to the recipient. > > Locally, the ringing voltage is 90V RMS, riding on the normal > on-hook DC of > about 50 volts. > > 73, > John > -- The Information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful.