Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!uw-june!uw-entropy!dataio!pilchuck!ssc!mcgp1!jgo
From: jgo@mcgp1.UUCP (John Opalko, N7KBT)
Newsgroups: sci.electronics
Subject: Re: Using "Free" telephone power
Message-ID: <1879@mcgp1.UUCP>
Date: 3 May 89 19:25:34 GMT
References: <636@serene.UUCP> <2829@skivs.UUCP>
Organization: McCaw Cellular Communications, Inc., Seattle, WA
Lines: 24

In article <2829@skivs.UUCP>, dr@skivs.UUCP (David Robins) writes:
> 
> I don't know how it is now, but the old Princess and other Bell System
> phones had dials with incandescent bulbs, whcih were powered off AC by
> a small wall transformer.

The newer phones use an electroluminescent panel that is, indeed, powered
by the CO battery.

What I'm trying to figure out is how you folks who hang voltage dividers
and LEDs across your phone pairs keep from frying things when the ~100 VAC
ringing current arrives.  I imagine you can get a big, honking capacitor
that has a low reactance at 20 Hz and shunt it around the LED, but...  :-)


					
					John Opalko

					uunet!nwnexus!thebes!mcgp1!jgo


PS:

How much do 8,000 mfd non-polarized caps cost, anyway?  :-)