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DTMF Tone Generator Module - Now with schematic
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author DTMF Tone Generator Module - Now with schematic
Glitch Militia
Ok, So I dreamt this up.

Flickr Picture...

It's a DTMF Tone Generator module.

Think of it as a Logic DTMF tone VCO.

A DTMF chip responds a button matrix. So if we replace the keypad of phone with some CD4066's, we can control the tones by logic or trigger.

Say you have a bunch of logic osc, trigger or what not. All going to the matrix, it will only make tones when the "row" and "coloum" match up. And the corresponding tone will be played, for as long as either is active.

All DTMF Tone chips, also have "mute" and "any key out." Ofcause "mute" is self explanitory. The "any key out" is working like a trigger. And it will trigger whenever a tone is present.

A 4x4 L.E.D Matrix is used as visual guidance of when is triggering. Also there's inputs corresponding each row and coloum, for logic or trigger.

Also we have 2 CV inputs. Input one, controls the row, and input two controls the coloum. This way the module can also create tones just by recieving 2 CV signals. This would be implemented by some VU meter chip.

---------------------------------------------------------------------- --------

Anywaaaaays I've not built this yet. I just think it's a cool module. Would fit great in a lunetta synth.
Tombola
Cool idea!
iopop
Which DTMF chip did you plan to use? I have one in my parts bin that I plan to use when time for that is around.
Glitch Militia
I found a specific one did only required 12 v. Sadly I can not remember which one.

Some chips require 48 V. This is what they get from the phone line.
cbm
If you did it with individual oscillators, you could get different tones. You would need seven of them, though.

If you are by chance a Max/MSP user, I have a DTMF patch called PhoneTones available here: http://www.xfade.com/max/examples/
Glitch Militia
cbm wrote:
If you did it with individual oscillators, you could get different tones. You would need seven of them, though.


I'm guessing you mean polyphony, and not just different tones ? Because these chips do sertainly output 16 different tones. 8 "static"tones and 8 that is a mix of 2.

Also where are you pulling the number 7 from ? Should be 8

Here's the DTMF matrix:



----------------1336Hz------1633Hz
---------1209Hz-----1477Hz

697Hz------1-----2-----3-----(A)

770Hz------4-----5-----6-----(B)

852Hz------7-----8-----9-----(C)

941Hz------*-----0-----#-----(D)
richard_k
The DTMF keypad can be manipulated to get more tones from it. The philosophy is when you press any single key, you get the two tones from the intersection of that row and column. But, if you press two keys in a row or column, you can get that single frequency.

When Bell Telephone first came up with the idea for DTMF, they did some analysis for eight tones that would have no harmonic relationship with each other. Ultimately, that became the eight tones in use today. And, even though the standard user keypad doesn't have the ABCD keys, those were intended for command signaling.

You can still get DTMF chips. Look for part numbers TP5089, CM8888, CM8870, M-8870, 75T202, SSI-202, 75T204, SSI-204, MC145436, CD22202, CD22203 and 75T203. Occasionally, you can find DTMF tone generator chips in old telephones, too. I think there are a couple of public domain designs based on a Microchip 16F84 processor out there as well.
cbm
I was thinking of a standard phone pad, which has three columns and four rows. The standard phone doesn't have the ABCD 1633 Hz column.

When I mentioned different tones, I was thinking that rows and columns of the matrix could be detuned for a different "wrong phone" sound.

Other freq combos that may be of interest are 440 & 480 Hz, which is ring tone (roughly four seconds on, two second gap,) and 620 & 480 Hz for busy (roughly half second on and off.) These are fairly standard in the US, at least.
richard_k
Most of the DTMF chips used a TV color burst crystal at 3.579545 MHz as the reference and then divided down to get the precise tones. The only way to change the frequencies is to change the reference oscillator frequency.

Radio Shack used to sell pocket phone dialers that had the ability to store a dozen or more sequences of tones and would play them out a speaker. The idea was for travelers who used pay phones could store their calling card numbers and other telephone numbers and replay them on demand. The dialer had a small speaker that the user would place over the telephone mouthpiece.

The Radio Shack Pocket Dialer was a favorite for conversion into red boxes in the late 1980s. A red box would simulate the tone made when you drop a quarter into a pay phone. This would allow you to make free phone calls whenever you wanted. At first people would use small tape recorders for the tones but a pure electronic solution quickly became popular.* I remember a case where a young hacker on the east coast was caught with crystals and unmodified pocket dialers and he spent a couple of years in federal lockup for "intent to commit toll fraud." The problem was he hadn't modified the dialers but he was still convicted.

To convert the dialer into red box, you would change the crystal to something in the 5 MHz range (I forget the exact frequency). One idea to make the chip play other tones is to feed a voltage controlled square wave into the oscillator port. That would let you get a huge range of tones but you'd have to calculate what the exact frequency range would be based on the clock frequency. The ouput tones would be square waves but could be processed further by your filters in your synth.

Here is a data sheet on the TP5089 chip for your experimentation.

*Edit: There was a scene in the movie "Hackers" where this was done.
Glitch Militia
richard k: Would the MK5089 by Mostek be the same chip as you are referring to from National Semiconductor ? I can not find any datasheet on the MK5089, so I guess so.
richard_k
Yes, the Mostek MK5089 is a plug-in replacement for the National Semiconductor part. There were half a dozen manufacturers that made DTMF encoder chips and they all were pin for pin replacements.

You can find information from some of the old Bell Telephone documents at http://www.porticus.org/bell/telephones-technical_dials-touchtone.html   About half way down on the page is a reference to Bell Labs Technical Journal article from 1960 that explains the technical history of DTMF. Historically, it makes for interesting reading.

The Bell Labs Technical Journals printed in the years 1922-1983 can be found at http://www.alcatel-lucent.com/bstj/

I haven't been able to find any source for the years 1984-1995.

The years 1996-2011 can be found at http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1538-7305/issues

General stuff can be found at http://www.alcatel-lucent.com/wps/portal/BellLabs/TechJournal/
DGTom
cbm wrote:
If you did it with individual oscillators, you could get different tones.


or apply the same concept to multiplexers, so instead of the DTMF tones you can use any signal sources.
otherunicorn
Some DTMF chips also have two separate sine outputs, and an X-ORed digital output. I would also recommend against using the colorburst crystal, Use some other similar frequency, but not the correct one! I abandoned ideas of producing such a module years ago (I have a bundle of chips) because with phone dialing systems being being responsive to audio, music made with such a module could cause some unwanted phone calls!
Glitch Militia
Sorry to wake it from the graves MY ASS IS BLEEDING
I'm getting back into building again after a long break.
If I made a schematic would someone be so kind to proof read it?
Glitch Militia
Ok I did a "quick" schematic:

DTMF Tone Generator V.1

Would that work?

Also I'm unsure how to put LED's on all intersections. Currently there's only LED's on each input, and I'm unsure if it would work. Also I forgot to put resistors with the LED's They would also be obsolete, when you put LED's on all intersections.

Also I included a button matrix, to manually trigger the 4066's.

Further Improvements:

LED's on all intersections.

LTC1799 variable oscillator + CV

CV in. How would you implement this? VU meter chips, yes, but how?

Tone inhibit input.

Mute input.
KnobHell
Not to throw a monkey wrench in bere. But why not do this with a wave table? Isn't there a arduino sampler project out there?

The dtmf chip would be a fine way to go. But with the chips being in the gerasic phase using some new technology would make it much simpler to source the parts, and add versatility.
Glitch Militia
To be honest I just thought it would be fun with the DTMF chip.
KnobHell
Glitch Militia wrote:
To be honest I just thought it would be fun with the DTMF chip.


Ye, I can see that. I have a few chips I look at from time to time.

Repeat-ability is nice too.

It's your project. Just throwing in a different option.
daverj
Glitch Militia wrote:
richard k: Would the MK5089 by Mostek be the same chip as you are referring to from National Semiconductor ? I can not find any datasheet on the MK5089, so I guess so.


A bunch of companies made pin compatible versions of the 5089. About the only differences were the maximum power supply voltage. They were all designed to run at 3.5v to 10v. The max power voltage varied from about 13v to 15v depending on manufacturer.
plugugly
HA! I really can't get enough of you guys. Earlier this month I jotted a note in my note book above some sequencer UI doodling to the effect of "DTMF module. Could be interesting."

I'm looking forward to your progress on this.
KnobHell
So... Inspired by this thread I creadted the song below. Since I didn't have a tt gen chip handy I used two oscillators an my 569.

Just to give you an idea what you can do with touch tones.

Thanks for the inspiration!


[s]http://soundcloud.com/knobhell/1-800-555-1212-wav[/s]
Glitch Militia
Awesome! Now more randomness!
Grumble
otherunicorn wrote:
because with phone dialing systems being being responsive to audio, music made with such a module could cause some unwanted phone calls!

I have experienced something similar.
During my military service we could receive a radio station with music and transported the music over a telephone line (also using a military transmitter from a phone network) but when the theme song of the advertisement block was transmitted it was translated into a ring of the phone, making very loud noises into the speaker zombie
[s]https://soundcloud.com/jingleweb/ster-radiojingles-montage-jinglewe b[/s]
windspirit
Fyi tayda currently carries a dtmf encoder/ decoder chip that I have been messing around with. Hopefully something to show soon.
robstave
Here is a version I did a long time ago with a picaxe
(all it did was generate the random bits and control speed)

https://www.youtube.com/watch?v=8LuiuNOnrh0

Schematic is on the Electro Forum.

http://electro-music.com/forum/topic-28865.html
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