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.

Author: Mosida Brara
Country: Mauritius
Language: English (Spanish)
Genre: Politics
Published (Last): 23 September 2009
Pages: 470
PDF File Size: 6.32 Mb
ePub File Size: 16.82 Mb
ISBN: 761-2-81691-941-1
Downloads: 15481
Price: Free* [*Free Regsitration Required]
Uploader: Tojagor

I suspect that when I changed the resistor from k to 10k, I would have needed to change something else as well.

Need a Current Regulator? Keys A, B, C, and D on the telephone keypad are used for special signalling and are not available on standard pushbutton telephone keypads. May 01, When a key is being pressed on the matrix keypad, it generate a unique tone consisting of two audible tone frequency.

DTMF Decoder – MT [] : Sunrom Electronics/Technologies

It also analyzes transistor’s characteristics such as voltage and gain. Schematics and BOM is provided below for your reference.

You have entered an incorrect email address! I can now confirm that the phone is not the problem.

It never occured to me that the phone might stop putting out the signal. Logged jwatte Supreme Robot Posts: I would get a audio amp kit from Velleman or sparkfunto fecoder with the decoer. Use a Voltage Regulator! This circuit can be interface to a computer, allowing caller to computer interaction.

The problem is something with the circuit. Transient protection may be achieved by splitting the input resistors and inserting zener diodes ZD1 and ZD2 to achieve voltage clamping. This still did nothing. Therefore, by adding an extra resistor and steering diode the tone duration can be set to different values.


One can also test the IC on a simple breadboard. However, for other applications like remote controls and radio communications, the tone duration may differ due to noise considerations. Discussion in ‘ The Projects Forum ‘ started by techadiyaJan 11, DTMF is as acronym for Dual Tone Multi-frequency Signaling it is used in telecommunication signaling basically it is a signal that is sent to the switching center phone company when the phones keys are pressed.

At least we learn as we fail. I tried unplugging the power and plugging it back in. Feb 13, 9. It’s small, power efficient, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors. Connect local telephone and the circuit in parallel to the same telephone line.

This reset all the lights set them all to off but they still wouldn’t respond to keypresses. This seemed to cause a slight “lag” in the response time, but it still locked up the same. You may purchase MT chips and 3. Mar 11, 5. The phone is putting out sound the entire time. He said that his circuit worked fine after replacing that k resistor with a 4.

DTMF Decoder Using MT

It seems as if unplugging the phone from the circuit works sometimes. With the 10k resistor in place, as soon as I fired up the circuit and started hitting buttons on my phone the LEDs started reacting exactly as they were supposed to.

Millions of engineers and scientists worldwide use MATLAB to analyze and design the systems and products transforming It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Switch on decorer switch S2. Here is dtmg link to the datasheet for the MT http: It is a common standard build into the decoder chip. Logic 0 Detection of dial tones is reflected on the bit Dfcoder, while the output Q4, Q3, Q2, Q1 indicate the dial tone that is being detected on the telephony system.


But, again, after a few seconds it stopped responding. Yes, the cellphone is connected to the circuit by the audio jack. We’ll be wrong a lot of the time.

I understand that the resistors at the top left of the diagram are for controlling the op-amp, but I don’t understand exactly how they do that. April 30, Notice that there are key tone for A B C and D. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground.

DTMF Decoder – MT8870

After some playing around aimlessly, it started working decodee. May 02, But then another problem arose. Logic 0 release from button ‘2’ TOE: You can control lights, fans, AC system, computer, printer, amplifier, robots, garage door, security systems, motor-driven curtains, motorized window blinds, door locks, sprinklers, motorized projection screens and anything else you can think of. Basics, Usage, Parameters and Applications.