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From: kludge@gitpyr.UUCP (Scott Dorsey)
Newsgroups: net.analog,net.ham-radio
Subject: Re: Telephone ring detector
Message-ID: <1575@gitpyr.UUCP>
Date: Thu, 20-Mar-86 18:13:22 EST
Article-I.D.: gitpyr.1575
Posted: Thu Mar 20 18:13:22 1986
Date-Received: Sun, 23-Mar-86 11:15:51 EST
References: <2032@orca.UUCP>
Reply-To: kludge@gitpyr.UUCP (Scott Dorsey)
Distribution: na
Organization: Georgia College Of Universal Knowledge
Lines: 27
Xref: dcdwest net.analog:714 net.ham-radio:3161

In article <2032@orca.UUCP> philb@orca.UUCP (Phil Biehl) writes:
>
>	I'm in the process of adding telephone capabilities (autopatch)
>	to the UHF ham repeater I am working on. I would like to be
>	able to detect the ringing current produced by an incoming
>	call. What I need is a CMOS compatible signal indicating that
>	ringing current is present on the drop. That is, a pulse for
>	every ring burst.

  My suggestion is one of the neon optoisolators on the market.  Just
hook one end to the phone line and the other one to a 741 op amp.  Or,
taping an NE-2 bulb to a CDS cell will probably work, although I wouldn't
bet on reliability.  I know that HP makes some neon optoisolators, but
you can probably get them cheaper...


-- 
-------
Disclaimer: Everything I say is probably a trademark of someone.  But
            don't worry, I probably don't know what I'm talking about.

Scott Dorsey       " If value corrupts
kaptain_kludge         then absolute value corrupts absolutely"

ICS Programming Lab (Where old terminals go to die), Rich 110,
Georgia Institute of Technology, Box 36681, Atlanta, Georgia 30332
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