DTMF Hack – How to Make a DTMF Decoder!

DTMF Hack – How to Make a DTMF Decoder!

Posted on January 30, 2010 by max


You know, DTMF is probably out of use now because it’s mainly used on analog wired telephones.  When you press numbers to call someone on your grama’s telephone, you are basically making DTMF tones.

For those of you who want to mess around making your own spy gadgets, you might want to learn how to make a DTMF decoder.  I really think that you would be far better off making a GSM-hack device of some sort that would be able to hack GSM signals.   Well, just a thought.

Genave - DTMF Explained
DTMF Explained - How it works, and why it's employed as a signaling format. ...
Sure, the tone 697 is the same for both digits, but it take two tones to make a digit

At the very least, learning how to make DTMF decoder is one of the most basic circuitry you “should” learn if you don’t know how to already.

How to make DTMF decoder connected to cell phone ... - YouTube

“The heart of this device is the MT8870, which is a DTMF to BCD decoder chip. It takes an analog audio input, and converts that to a 4-bit binary output. Those 4 bits are put into a BCD decoder, and that converts that into the corresponding 0-9 output. Various other devices were needed to complete the board, and can be seen in the board layout below.

LucidScience - Build the PHONE NUMBER DECODER - Page 1 of 7
When you press the numbers on your phone to make a call, the tones you hear
are called Dual Tone Multi Frequency tones (DTMF), and they represent one of ...


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