[Brad] over at LucidScience decided that it would be useful to have a DTMF decoder on hand, and got busy building one. His DTMF decoder box uses a CM8870 DTMF decoder chip, which you might assume ...

DTMF Encoder Decoder is very easy to use the program to decode DTMF dial tones found on telephone lines with touch-tone phones. • DTMF is the global standard for audible tones that represent the ...

The project uses a DRA818 VHF/UHF transceiver plugged into a low-pass filter combined with a hardware DTMF decoder ... sheet of transfer paper around the board to align both layers.