Path: utzoo!attcan!uunet!n3dmc!johnl
From: johnl@n3dmc.UU.NET (John Limpert)
Newsgroups: sci.electronics
Subject: Re: Need DTMF Decoder/Ringing Detector
Keywords: Need IC's to detect ringing and decode DTMF touch tone signals.
Message-ID: <380@n3dmc.UU.NET>
Date: 8 Jul 88 01:07:51 GMT
References: <5317@super.upenn.edu>
Reply-To: johnl@n3dmc.UUCP (John Limpert)
Distribution: na
Organization: N3DMC, Silver Spring, Maryland
Lines: 33

In article <5317@super.upenn.edu> zielke@eniac.seas.upenn.edu (Stephen Zielke) writes:
>4. Dectecting the DTMF touch tone signals is the main problem.  There are
>   plenty of DTMF encoders that are used in the telephone (accepting
>   signals from a keypad).  But the DTMF DECODER, which would be present
>   in the central office, seems to be more difficult to find.  Anyone know
>   where to get one of these chips?

This month's QST magazine has a couple of ads for DTMF decoders.  They
are small PC boards with 3-4 chips.  Both boards appear to have a LSI
decoder chip.  If you don't want the whole PC board, you might be able
to talk them into selling the chip by itself.  Whatever you do, avoid
designing/building a decoder that uses the NE567 chip.  I have seen
alot of these that were ripped out and replaced with a single chip
decoder design after the builder got tired of tweaking the decoder
circuits every month.  Nothing wrong with the NE567, it's just the
wrong chip for this application.

NET-KALL NK-1 (34.95 KIT 44.95 ASSEMBLED/TESTED)
MoTron Electronics
695 W. 21st Ave.
Eugene, OR 97405
1-800-338-9058 or 503-687-2118

TD-16 (44.95 KIT)
NorCon Engineering
P.O. Box 1607
Mooresville, NC 28115
704-664-7817

-- 
John A. Limpert
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