This tutorial introduces you to DTMF technology and the DTMF decoder IC MT It also helps you to understand how to interface the IC to based micro . This board decodes DTMF signal either from an audio source or phone line to 4 bit binary TTL(5V) level output. It also indicates outputs with LED. Can use. Introduction. DTMF (Dual Tone Multi-Frequency) signaling is used for telecommunication signaling over telephone line in the voice frequency band between.

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I’m dead sure about the connections of the circuit. Design Guides Product Development: Again because when you’re not pushing buttons it decides there are no longer ear phones connected.

The telephone exchange center will generate a high voltage signal to the receiving telephone, so as to ring the telephone bell, to notified the receiving user that there is an incoming call. You May Also Like: Millions of engineers and scientists worldwide use MATLAB to analyze and design the systems and products transforming The phone is putting out sound the entire time.


Aug 23, 1 0.

Mar 11, 5. Logic 0 ‘1’ press and hold TOE: These digital bits can be interface to a computer or microcontroller for further application eg.

DTMF Decoder – MT8870

But if I stop pressing anything for even five seconds, it locks up every time. Jan 4, 3 1. The circuit also provides an excellent bridging interface across a properly terminated telephone line. After some playing around aimlessly, it started working again. A complete communication consist of the tone generator and the tone decoder.

Switch on auxiliary switch S2. I’ve seen modern electronics sense if a connector is unplugged or shorted and shut off. Now the high logic at pin 5 enables the detection of tones representing characters A, B, C, and D. Logic 1 ‘2’ press and hold TOE: You need to make the phone think there are ear phones connected all the time.

Any assistance in helping me to stop it from locking up is appreciated.

Feb 13, 1 0. On Sale Offers New Products.

DTMF Decoder Using MT

It’s not late until its two, then it’s too late. I made deoder project on a breadboard. It is a common standard build into the decoder chip. Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption may be supplied from a single 9V battery.


Dtmmf on May 02, Figure 3 shows the basic circuit for You can take pictures of your waveform, to analyze later, or pass to other techs for their advice. Jan 13, 3.

DTMF Receiver IC MT Tester | Electronics For You

If not, then I would suggest getting one of those is the first thing you should do. The tone-pair DTMF dual-tone multi-frequency generated by pressing the telephone button is converted into binary values internally in the IC. Please enter your comment!

The MT is an pin IC. Try using a K resistor and see if that clears it up. Log into your ftmf. Use a Voltage Regulator!


I have tried using two k resistors in parallel for a resistance 8870 50k. I will try getting a headphone jack splitter and plugging in a set of headphones with the phone and circuit board, so I can listen and make sure the phone is putting out the audio signal.

Aug 23, 7.