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From: Gerry Schneider
X-Mailer: Mozilla 4.73 [en]C-SYMPA (Win98; U)
Subject: Re: Telephone Ring Suppressor
Date: Mon, 23 Sep 2002 19:14:10 -0700
NNTP-Posting-Date: Mon, 23 Sep 2002 19:35:44 EDT
Organization: Bell Sympatico
Allan Herriman wrote:
> On Sat, 21 Sep 2002 14:45:51 GMT, George
> >In article ,
> >Jim-T@analog_innovations.com says...
> > > Awhile back I posted an inquiry about a telephone ring
> > > suppressor that could be switched in and out.
> > > Rummaging through my junk pile looking for something
> > > else I found it and snapped it apart... see photo on
> > > alt.binaries.schematics.electronic
> > > Message-ID:
> > > It's nothing more than a full-wave rectifier that can be
> > > switched in or out of the telephone circuit.
> >I don't understand why this works. Also, is it possible to
> >make an outgoing call if the ring suppressor is turned on?
> >Well I guess it would be since most phones these days have a
> >FWBR at the front end. But I still don't understand why it
> >works to suppress ringing.
> Ring detectors are usually (but not always!) capacitively coupled.
ALWAYS in N. America. See FCC part 68.
> The capacitor may be 1uF or so (it varies from country to country and
> from device to device - do a web search for "ringer equivalence
> Without Jim's FWBR -> the AC ring signal gets coupled through the
> series cap to the 'bell'.
> With Jim's FWBR -> the series cap gets charged up, and no current
> passes through the 'bell' after the first few cycles.
> Note that the 'bell' typically includes its own FWBR, but there's a
> big difference between AC coupling before and after a rectifier!
> The outgoing call uses DC signalling, and isn't affected by the FWBR.
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