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DTMF Decoder help...

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Rescue1

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Hello all, and Happy Holidays,

I would like to build a simple DTMF decoder. Basically I want to use the audio output of an old 2 way radio to connect to a DTMF IC(Probably the 8870), and into some sort of binary decoder or the Arduino so I can get single outputs. I want this circuit to integrate into my home automation setup through my HAM repeater for when the internet is down, which happens a lot when the power goes out even though I have a backup generator. I have searched around and found some good info, but want to see what others have done. Thanks a bunch for the help....:)
 
Years ago the popular chip for this was the now obsolete 567 Tone Decoder. Check out the old data sheet and note the circuit example shown on page 6 which gave a logic high corresponding to one of the 12 DTMF tones. Note how the 7402 is used. The popular trick at the time was to use an old set of 27 MHz CB walkie talkies to transmit the tones. One would transmit tones from a DTMF encoder while the other received the tones and the inputs of the 567 chips were coupled to the speaker of the receiver walkie talkie.

**broken link removed** is available from Allied Electronics (and other suppliers).

Anyway, maybe something along those lines?

Ron
 
Thank you all for the help, I will start investigating these IC's and see if I can whip up a circuit..:)

Maybe I can utilize what you guys are saying and add the modern Arduino twist so I can have multiple tones operate something.. So basically say, 1234 will give an output from the Arduino, and 5678 will give another.. Hmmm, lots of thinking to do..Thanks again..
 
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