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 UUCP: johnl@n3dmc.UUCP, johnl@n3dmc.UU.NET, uunet!n3dmc!johnl PACKET: n3dmc@n3dmc.ampr.org n3dmc@wa3pxx