Article View: sci.electronics
Article #7666DTMF Decoder IC
From: Gordon Hlavenka
Date: Tue, 09 Oct 1990 05:55
Date: Tue, 09 Oct 1990 05:55
27 lines
1361 bytes
1361 bytes
After you get this thing replaced, do this:
input ----||---/\/\/\/---+----+------to decoder input
1uF 1.2K _|_ |
\ / ---
V A (Silicon diodes, like 1N4148)
--- /_\
| |
+----+
|
GND
This should block the ring voltage for you... It takes off any DC, does a
current limit (which shouldn't affect sensitivity since the decoder input is
Hi-Z) and then limits the voltages to 1 diode drop -- about .7V
Plenty of signal is left over for the decoder, but ring voltage is reduced
to non-injurious levels.
If you're looking for _any_ DTMF decoder, look for the SC11204 from Sierra.
(Sierra: 408-263-9300)
-----------------------------------------------------
Gordon S. Hlavenka cgordon@vpnet.chi.il.us
Disclaimer: Sierra who? Never heard of 'em!
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<27114b84-483.1sci.electronics-1@vpnet.chi.il.us>Path:
arc1-ca.pugleaf.net!utzoo!attcan!uunet!decwrl!wuarchive!zaphod.mps.ohio-state.edu!uwm.edu!linac!tellab5!laidbak!obdient!vpnet!cgordonReferences:
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!decwrl!wuarchive!zaphod.mps.ohio-state.edu!uwm.edu!linac!tellab5!laidbak!obdient!vpnet!cgordon From: cgordon@vpnet.chi.il.us (Gordon Hlavenka) Newsgroups: sci.electronics Subject: DTMF Decoder IC Message-ID: <27114b84-483.1sci.electronics-1@vpnet.chi.il.us> Date: 9 Oct 90 05:55:03 GMT References: <14793@mentor.cc.purdue.edu> Lines: 26