|
The second part is the tricky part. A normal telephone system uses only two wires to send both the microphone and the speaker signal. From basic electronics you might know that you need 2 wires to send a signal, and at least 3 to send 2 signals, because one of the wires is acting as a reference (usually called ground).
In a telephone system both the mic and the speaker signal are multiplexed into one signal. To be able to connect your phone to you mic-in and line-out of your pc you have to de-multiplex these signals. The solution of Chris was to extract the mic an speaker signal before it is multiplexed inside the phone. But this can also be done by a transformer (which is also used to prevent the 9V DC from going into you soundcard). The kind of transformer used for this application is a so called secondary centre tapped transformer. Meaning that it has 2 connections at its primary side (where the telephone will be connected) and 3 connections at its secondary side. The middle connection is physically connected to the middle of the secondary coil of the transformer. This middle connector is used as a shared ground for both the mic and the line-out.  Another issue is the input impedance of a phone line. When a phone line doesn’t see the right input impedance reflections will occur, resulting in echoes or even in disabling the line. A telephone line has a input impedance of 600 Ohms, so the transformer has to be a 600 Ohm transformer. At the secondary side of the transformer a 150 Ohm resistor has to be placed at the middle connection to make the secondary input impedance 600 Ohm as well, resulting in a balanced transformer. This all might seem complicated but as can be seen from this figure, the circuit is pretty simple and small. |
 For the connection to the pc jack-plugs have to be used, usually these arestereo. For the microphone connector the left and right signal can be simply connected to each other at the circuit connection, so actually you make it a mono signal. For the speaker connection one of the left or the right signal should not be connected because your soundcard stereo output would be shortcut otherwise. (In most scenarios this won’t matter though as the sound from both channels are the same.) One funny thing is that it doesn’t matter which connector you plug into mic or headphones. The result will be the same as we have the transformer in-between the two cables. For the telephone connector a RJ11 female connector should be used, so you can attach any phone to your device. Everything can then later be put into a nice little box, and -hey!- let’s use a ADSL splitter. It will provide us not only with the RJ11 that we need but also a neat little box. |
On the next page we’ll have a look at the step-by-step building instructions.
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June 30th, 2005 at 6:59
hey this sounds like a really good idea and all but is it possible that you guys can publish a little more straightforward guide with steps and pictures for each step. because i have no idea how to do what is listed above, and i want to learn.
June 30th, 2005 at 8:47
Thanks for this description! Almost sounds too easy to be true
Maybe it’s a good idea to tell us the part number for the transformer or where you got it from?
I have been looking on the www.conrad.nl site, but I am not sure if they have the right tranny or which one I should get.
@dimo: there’s not much to tell is there? Only thing that isn’t clear is what’s + or - on the 9v battey or phone connection,
but I guess that’s very easy to find out; only 2 possibilities
Thanks again
Franc.
June 30th, 2005 at 8:55
a telephone line is symmetrical, meanding that the polarity is not an issue, meaning that you don’t have to worry about your + and - of the battery.
June 30th, 2005 at 8:56
Oh, one suggestion for the speakerjacks: I’d say, on both jacks, connect the tip only and not the ‘ring’. This way it really doesn’t matter where you
put microphone or speaker.
Franc.
June 30th, 2005 at 8:58
As mentioned in the text, the transformer isn’t easy to find. But the Bourns lm-np 1002 of 1004 will do the trick…
June 30th, 2005 at 10:56
dimo: I’ve added a step-by-step instruction to the article. Hope you like it
June 30th, 2005 at 17:26
any plans for a usb version??? like one that uses usb opposed to jack-plugs for input/output? like a normal usb phone?
June 30th, 2005 at 17:51
Jax: Not really. But THAT would be nice.
The problem then is that you would need several active components as well as drivers for it. Basically POTS to Analog audio + Audio to Digital audio + USB controller. It would not be ‘economically feasible’.
You could of course use an USB audio card and then add the converter on this page to it.
June 30th, 2005 at 18:16
I’ve built this circuit - it’s documented here: http://www.tkk.fi/Misc/Electronics/circuits/teleinterface.html#simplehybrid
If you’re going to use the battery, don’t forget you need a transformer that can sustain 15mA or more of DC current. From digikey, lowest price first:
Tamura TTC-105-1
Triad TY-145P
Triad TY-401P
Tamura TTC-109N-1
Note also that SOME phones, especially cordless ones that have their own power supply, will work fine WITHOUT the 9V battery.
June 30th, 2005 at 18:35
It’s just the classic phreak box “The Rock Box” or a Rat Shack phone recorder, but it’s the idea that counts. Great idea!
June 30th, 2005 at 22:09
I’m having a hard time finding the transformer in the Netherlands. Anywhere I can salvage this from? An old modem perhaps??
June 30th, 2005 at 22:30
Build your own Chat-Cord
Voice over IP is taking over the world and I also like the idea of calling for free… The problem I’ve experienced so far is the fact that you always have to use those cumbersome headsets. When it would be possible to use your standard phon…
July 1st, 2005 at 1:47
Dude is it possible to make a more organised tut because this is really hard to follow?
July 1st, 2005 at 3:18
here’s a link to a transformer. not sure if they do international shipping. http://www.mouser.com/index.cfm?&handler=data.listcategory&D=553-TY304P&terms=553-TY304P&Ntt=*553TY304P*&N=0&crc=true
July 1st, 2005 at 12:15
I’d be interested if conrad.com has the transformer? Or has anyone else had any luck finding it somewhere in Germany.
Thanks
July 1st, 2005 at 14:56
Build your own Chat-cord
Jeroen over Grynx has done a very good DIY on building your device to connect your normal phone to PC. There is a similar device on the market called Chat-Cord but it is quite expensive - so why not make your own:
Not too long ago I ran across a …
July 1st, 2005 at 17:10
This is a great Idea, just What I’e been looking for for a while. I’ve been looking in an old modem for a transformer, but will it be the rtight kind of thing? Also, how do you tell if it is centre tapped or not?
July 1st, 2005 at 19:18
Good job. i just had a question. would these be the required parts i would need:
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=281088
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=340724
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=428353
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=341609
July 1st, 2005 at 23:15
I got up with a small idea to make the phone USB.
There are very small USB Sound blasters for sale,
on ebay you can get them as cheap as 6 euro!
In combination with the Chatcord you have the advantage that
you can also play your MP3`s and Skype all the way.
Altough you must be able to chose a Soundblaster for both actions.
http://www.usbgear.com/usb-audio-adapter/usb_audio_blaster.html
July 1st, 2005 at 23:19
Oh forgot to say that with the shipping costs of ebay it will ofcourse
be a bit more expensive, but cheaper than a converter or other phone….
July 2nd, 2005 at 0:46
Actually a few weeks ago I was thinking about something a bit different. How about writing a Skype to SIP gateway. That’s because of an offer of 1und1.de of a calling ‘flatrate’ for around 10/month to any landline in Germany.
If I had such a gateway, I would offer people free calls to numbers in Germany, maybe asking them for a small donation if they use it a lot, so I can cover my expenses.
However, I didn’t find any OS or free (as in beer) configurable SIP client to connect this to… I’ve lookep a bit into the Skype API, and it seems connecting to Skype should work (one problem being that Skype needs to connect to a soundcard, so I would also need a ‘virtual’ soundcard, if I don’t want to connect two soundcards together) or connect the phone line to the soundcard (my modem/router handles the SIP translation). Also this probably wouldn’t work directly with the device presented here as it tries to emulate the side of the phone-company. I’d have to emulate the phone.
What do you think of this idea, would you place a call through a Skype-VOIP-PSTN gateway (privacy implications…)?
Maybe you know of a solution already?
Kind Regards, Florian
July 2nd, 2005 at 17:31
Hmmmmmm, now if it only supported pulse dialing so that I could make Skype calls with my rotary phone……..
July 2nd, 2005 at 20:17
Poor Man VoIP
… que soluciona el problema utilizando un telefono casero. Los detalles los encuentras en la página de Grynx
July 4th, 2005 at 7:47
One other thing you may want to think about - there are any number of USB sound dongles around, then you can put the skype audio through the USB device and keep the PC speakers for other sounds. You would stick the USB dongle into the box with the 600/600CT transformer, and the whole thing would be pretty neat and tidy.
I think that has a future?
July 4th, 2005 at 12:32
Hi. i have a question. i would be glad if anyone help me.
I have a cordless phone and the phone has its own power supply, so i don’t need to use the battery or use the usb cable?
in other words..(having a cordless phone that has its own power supplu i don’t need to do the step 5(Connect the + from your battery (or USB cable) to pin 6 of the transformer) and the step 6 (Connect the - from the battery to pin 3 of the RJ11 plug.)???
Thanks!!!!
July 4th, 2005 at 13:09
Bruno: I can’t tell for sure, I think it depends on your phone. I have tried a Philips and a Siemens DECT cordless phone which both do need the supply voltage. But, there are other people who have cordless phones that do not need the 5 of 9 volt supply… So what I suggest is that you just try if it works without, and if it does not, include the USB/battery power supply.
July 4th, 2005 at 16:43
hmmm.
how universal is ths telephone interface?
should this circuit work on telephone networks around
the world or is it based on some north-american specific telephone standard?
basically, am I going to get an angry
call from my provider? well, probably not a call
on my landline…
July 4th, 2005 at 16:59
dirk: this is universal…
But you might understand it wrong, this device is placed between your pc and your phone, it is not connected to your telephone line at all… So it is off course not illegal or something and your telco won’t notice you using it.
July 4th, 2005 at 17:43
it’s compatible with mac ????
July 4th, 2005 at 20:22
diego: Yupp! As long as you have sound in and out. Duh!
July 4th, 2005 at 20:39
Out of curiosity, should this thing work in the United States as well? The reason that I ask is I’m pretty sure the phone systems in Europe may be different (in terms of voltage, etc), and that could affect this thing… Has anyone had any success getting it to work in the US?
July 4th, 2005 at 20:59
D’oh, just read post 28 and realized my question was redundant… Whoops
July 4th, 2005 at 22:57
how about the Echo? is there any? thanks!
July 4th, 2005 at 23:14
Bruno: As long as you turn off the 20dB microphone boost in the volume controls no echoes due to the “chat-cord” will occur. What does happen is that you hear yourself talking DIRECTLY in your phone’s speaker. But this occurs in normal telephony as well (even if you might not realise it, just listen carefully
) and is inherent to the way telephone-lines are built. Because this happens directly it is not annoying.
July 5th, 2005 at 8:05
Is there any way to make your own isolated transformer?? maybe if anybody tell us the awg and others details form the transformer, or tell us from where can we take this issue from old cards or devices
July 5th, 2005 at 12:59
Oh wow! This is such a great idea, the guy that invented this (Mr.Blond)is such a genius!
I hope that he calls his girlfriend every night, just to enjoy his chat-cord. Congrats and good luck to you all builiding it!
July 5th, 2005 at 16:23
Build your own Chat-Cord
Build your own Chat-Cord…
July 5th, 2005 at 18:44
Awesome! I can’t wait to try this.
July 5th, 2005 at 19:50
Nice and simple… I’ve got a Logitech usb headset that’s going to be modified a bit
Maybe this could be expanded with a PIC/other microcontroller to allow selecting skype / POTS from the phone - THAT would rule
July 5th, 2005 at 20:09
If a cheap voice modem can function as an IVR (Interactive Voice Respond) or Answering machine, why can’t we turn it into this Chat-cord device? Everything is already in this voice modem. The RJ11 jack, power, sound device. I am not a programer myself, but I am sure using Skype API and TAPI (Telephony API) can definitely do the job. I wonder if I can start my own company for this idea. Heheh Well, not that I mentioned on internet, someone else will do it. Not being a show off, but 8 yrs ago when I first used “IP Phone” (Yes, a software company called IP Phone), I already thought about bridging VoIP to PSTN because I live in America and many relatives are over sea. But at that time, I was using analog 14.4k modem and don’t have 2 land lines, anyway, don’t mean to go tangent.
With this combination (Voice modem, Skype API, TAPI), we can bridge VoIP to PSTN. Basically function as an ATA. I read voip-info.org once in a while. But the people there are guru. If no one think of this idea, I am sure there are some issues implementing this. Is it because voice modem has only one sound device so it cannot work in full duplex? Or is it because people at voip-info are perfectionist and they don’t want to use voice modem because it cannot be fully compliant as a FXO? For home user, we don’t really need to make our PC to be 100% FXO. We just need to be able to record and playback wav to the PSTN line. We don’t care about timing, etc. The voice modem can detect all that (valid dialtone, busy signal, fast busy, etc) for us.
So is there any guru here can explain why can’t we make a voice modem to bridge Skype and PSTN?
July 5th, 2005 at 20:39
In response to post number 31. European and US phones use the same voltages. I’ve used phones (and modems/fax machines) purchased in the USA in Europe without any problems.
July 5th, 2005 at 21:57
I have an idea for a USB version. I haven’t tried it, but maybe someone here can comment on the feasibility.
Could the wires from an inexpensive USB headset with microphone be used to build a USB-only version?
July 5th, 2005 at 22:08
How about using a modem to do this? Does anyone know how? Could you simply supply 9V to the phone line and hookup the phone directly to the modem? Seems like it would require less hardware and be easier to interface with telephony apps?
July 5th, 2005 at 23:03
Let’s say I decide to disconnect my home’s internal phone wiring at the demarcation point. If I plug this DIY device into a wall jack — allowing all the phones in the house to access the VOIP service — is there a guide on how much more power I should budget for?
July 6th, 2005 at 0:11
Robocoder, if you do not have service from a telco, you would assume it is not connected to the CO. However, technician sometimes make mistake or they don’t bother to really disconnect all the wires. If somehow the CO ring your line, it’s going to send you the ring voltage. If you equipements are not properly protected, it will fry them.
July 6th, 2005 at 0:47
I’ve found everything on Digikey except the “Print Board”. I’ve wanted to use print board in project before, but have never been able to find them. I’ve also heard them called by different names before (I forget which, off hand.) Anyone know anyplace I can get these? These are way handier than doing chemical etch circuit boards, but still more perminant than breadboards (plus I’m sure they’re cheaper than chemically etching, and I won’t have access to the school forever)
I live in the states. Thanks!
July 6th, 2005 at 0:50
The chat cord is listed at $23.99. Not that expensive.
July 6th, 2005 at 0:51
Hey! They call them “Prototyping Boards” I guess. Find a bunch on Froogle over here:
http://froogle.google.com/froogle?svnum=10&hl=en&hs=hBG&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&tab=if&scoring=p&q=prototyping+board&btnG=Search+Froogle
July 6th, 2005 at 1:24
You’re right, if it’s only 25 bucks you’ll be hard pressed to build a cheaper one… but what if the parts were free?
Observe: every cordless phone and answering machine already has this circuit. If you have a broken or useless instance of one of these devices, take it apart, use the parts, or just solder plugs to the audio taps on the board.
July 6th, 2005 at 2:09
Hi, i have another question, i don’t have here is my house the battery and the usb cable.
will the device(chat-cord) work if the baterry or the usb cable isn’t installed?
i’m sorry if my question is stupid, but i still don’t understand the purpose of the battery
thanks!”
July 6th, 2005 at 3:17
If you already have a soft modem…
I have an AC’97 AMR modem as part of my laptop. In Linux it shows up as a second sound card with no proprietary driver required; it is capable of recording and playing back audio at a phenomenal eight kilohertz! (That’s what the phone company uses to transmit normal phone calls. No good for higher quality voice recording though, which might be fun to do with a good telephone headset and a chat cable.)
Trick 1: a normal phone cable plugged from the wall to the laptop lets me record whatever’s happening on the phone line into the laptop. It seems like it’s always off the hook oh well. Maybe I’ll do this if I get a podcast and want people to call my land line.
Trick 2: With some skill you too can construct the SuperTellyUltraCable to connect your phone directly to the voice modem. Warning: no warranty. May break your phone or modem. The SuperTellyUltraCable is a normal phone cable. Two wires connect the phone to the laptop. Wire a nine volt battery in series with one of these two wires. Now you too can speak and play back with your telephone headset.
July 6th, 2005 at 3:42
Bruno, RTFA. Particularly this part:
First of all the normal telephone line has a certain voltage, depending on the state of the line….. So to be able to use a normal phone to make it think a call is going on, the phone has to see a 9V DC voltage at its input. This can simply be achieved with a 9V battery.
July 6th, 2005 at 3:53
Hey guys. To detect a ring in skype, a simple LC circuit could be used.
(http://en.wikipedia.org/wiki/RLC_circuit will interest you)
Here are the steps you would use.
1. Create a ‘ringtone’, i.e. wave/mp3 file in an audio studio type app
(maybe Audacity, its free and it’ll do it)
at a specific frequency, maybe 18khz. Or, you could grab your favourite
ring tone, and mux a tone over the top of it at barely audible levels
(audacity will do this too). Using a high frequency like 18khz means you
wont be able to hear it.
2. Build a circuit. What we need this circuit to do is filter all frequencies
bar our specific frequency, then use this frequncy to trip the circuit to
pump out 100vac to the phone, hence, making it ring.
To determine what components will be needed to
detect a specific frequency use the equation listed on the above mentioned
wikipedia page… An inductance value of 0.00008H and a capacitance
value of 0.000001F will give you a resonant frequency of 17794.06 (17.8khz).
This is basically a notch filter setup, but we will be using it to filter
out everything BUT the frequency the notch is setup for.
Using an Op amp, a resitor, a capacitor and a potentiometer, you can
then use the OP amp output to trigger the ring circuit… Anyone want
me to invest more time in explaining? Or will it be wasted?
July 6th, 2005 at 4:34
What I would like to see is a “converter” from telephone cord to USB. Where the device both is powered by USB and sends the signals to the telephone (something like an iMic, but with a phone jack.)
July 6th, 2005 at 4:43
I think they are called “USB modems”….
July 6th, 2005 at 4:47
my last question before buying the battery…. i will use this device(chat-cord) with and old telephone, it is a corded telephone
so i do need to buy the battery or don’t? (i don’t plan to do the usb version of the device(chat-cord)
thanks for help!!!!
July 6th, 2005 at 8:35
Yes. Yes bruno. Without any power source your phone will NOT work. The phone needs a voltage in the phone line in order operate and will not work if there’s no power. That power comes from either a) the battery or b) the USB. You NEED ONE OR THE OTHER. The only time you might luck out is if you have a telephone that plugs into the electric outlet already, but that is only a sometimes thing. Just assume you will need either the USB or a 9V battery.
July 6th, 2005 at 8:36
sorry guys… now i understand… the battery is necessary..
now i will start building the chat-cord…….
thanks!!!
July 6th, 2005 at 8:50
XCol:
Wouldn’t you need a 100v power source connected to the op-amp in order to get 100v output? I understand the bandpass filter, but I don’t quite understand how to hook up the op-amp to burst the 100v when I only have a 5v (or 9v w/ battery) power source available. Isn’t the op amp gain limited by the supply voltage on the +/- Vcc pins?
July 6th, 2005 at 9:03
Good thinking, XCol!! I understand your idea, and I haven’t thought of it that way. But it is actually a nice way to do it in hardware. I am only wondering of how to create the 100VAC… Maybe another transformer or something. Explaining something more sure isn’t a waste of time!!
p.s. if you prefer private conversation mail me at mr_blond18@hotmail.com
July 6th, 2005 at 9:31
XCol: I like your idea, couldn’t you use that “frequency trapping” circuit to trigger the phone’s internal ringing circuit (ie. figure out how to bypass the circuit that intercepts the ~100VAC and trigger whatever it triggered?).
.
I hope I explained that well enough, the lack of sleep is starting to get to me
July 6th, 2005 at 9:38
heh … nevermind, I thought this was http://www.grynx.com/index.php/projects/siemens-skype/
July 6th, 2005 at 10:56
Hi:
I was wondering how I can use this with an iBook. An iBook does not have a in jack or a Mic jack.
I am based in australia. has anybody tried it on telstra..
Suhit
July 6th, 2005 at 16:36
So is this the “rat Shack” box that will work?
If so, how do I hook the thing up? I already own a few of those.
July 6th, 2005 at 21:17
Radioshack Part #’s
2760148 - Dual PC Board - $1.79
2790355 - Telephone connector box - $3.99
4202434 - Mono audio cable - $3.29
2711109 - 5-pack 150 ohm resistors - $0.99
2731380 - Audio transformer - $2.99
And if you want that timer chip,
2761718 - TLC555 TIMER - $1.69
I haven’t decided what transitor and powersource yet, though. I’ll get it working first.
Yes, Radioshack is somewhat expensive.
July 6th, 2005 at 22:29
syberdave, the audio transformer you mentioned is a 1,000 ohm primary tapped, 8ohm secondary.
Since the circuit is needing a 600ohm on both primary and secondary I dont think this will do the trick.
You are welcome to try but 8ohm seems a little low when it should have 600ohm on the phone side of the circuit.
I would stick with http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=281088 as mentioned above in 18.
Also If anyone can find any old modems with an Atech ATS-127A transformer on it..
The specs on that are perfect for this project and actually have a better frequency response than the part at mouser.
I found one on my creative modem blaster 56k.
July 6th, 2005 at 23:03
In case ya’ll haven’t realized, the mic plug on pc’s is powered on the ring contact; this being said, I am not sure as to the exact voltage (18V I think), but with the proper resistor u could power the device with out the need for USB.
July 6th, 2005 at 23:33
OK, upon further research (and trying a voltmeter), the actual voltage is more like 3-9V depending on the PC. If your lucky you can still power the device in this manner.
July 7th, 2005 at 0:31
Soulhuntre-
No, the device you mentioned is just a recorder. That will let you hear what’s on the phone line. If you wanted to use that device to plug a phone into your computer you would have to add some voltage between the rat shack and the phone. (a 9v in series should work)
The rat shack will NOT let you plug from the speaker out on your computer to the telephone, though. You would be able to use your telephone as a microphone, but you would still need a pair of head phones to hear the computer. (There are two plugs on the “rat Shack”. One plugs into the microphone port, the other plugs into a CONTROL port to tell the recorder when to start taping. Not the same thing at all, really, and way more expensive.)
July 7th, 2005 at 0:36
Syberdave-
What’s the FlipFlop used for then?
July 7th, 2005 at 5:38
Okay guys, gettting 45vac (you really dont need 100vac, 45 will do nicely)
from a 5v circuit is a little more difficult.
That said, it is deffinatly not possible. There are 2 relativly easy ways to
do it. Way #1. Use a 555 timer, and an OP amp to genertate a 2vac
signal at 50 hz. (i say 2 volts because the opamp wont swing the whole 2.5v,
and ac is measured ground to peak, not peak to peak.)
Then use a 1:35-60 (anything in the 40-150vac range will make the phone ring)
transformer to step the voltage up. We need about 30ma, this setup should
be able to crank that out.
Way #2 Get onto an electronics site and find a small kit that will
invert 12vdc into 250 or 120 vac, then feed it 5vdc. Easy, providing
you dont fry your brain before hand.
Once you have decided your path its just a matter of making the ring
detection circuit trigger the ring voltage circuit. hell, here is an idea,
do this with a transitor/low voltage fet/op amp in the RLC loop
previously described (connect the gate or base of the device to the RLC
circuit, the collector to the + rail, and the emitter to the ring voltage
circuit… use a 100uf capacitor between the emitter and ground to flatten
out/filter the 18khz signal that is trigering the fet/transistor.
wanna chat some more about it? col_col83 at hotmail.com
July 7th, 2005 at 10:31
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July 7th, 2005 at 17:43
Is this possible with a transformer which has no center taps? I’ve got a bunch of modems but none of the T’s are center tapped, what would the changes be?
July 7th, 2005 at 17:53
As read in the article, the flip-flop could be used to generate the 100V AC at something Hz that you need for the ringer. (As XCol said above.)
I put my thing together and it works perfectly. Would it work even better if I got the right transformer?
Oh, I’m looking at my old modems (I have 2) and I think that I could take the transformer from them. That seems like a good idea, since I want to make another one so I could make a virtual PBX and have it connect to an outside line. (I have 2 sound cards.)
July 8th, 2005 at 0:26
Just a quick note for anyone following my radioshack part numbers. I bought the wrong mono audio cord. Mine only has one side, so I ended up taking another plug from an old microphone.
You’d want to get a double-ended one as shown in the picture in the article.
July 8th, 2005 at 0:35
Phil, you need one with center taps if you want to use both recording and playback at the same time. Otherwise, you could only have one. Half duplex vs. Full duplex.
And XCol, I think that there are features in the Skype API that let your computer know when it’s ringing. If the computer knows, you could use the Serial port to control a relay to start the ringing? Like if you would go through the trouble of making that detector circuit, you could probably make the serial-port thing easier providing you know how to program.
July 8th, 2005 at 2:10
The Radio Shack stereo cord:
4202387 - 6′ 1/8″ Stereo to 1/8″ Stereo Cord - $4.99
July 8th, 2005 at 7:17
Mr Blond,
Need a clarification:
[Quote]
5. Connect the + from your battery (or USB cable) to pin 6 of the transformer.
6. Connect the - from the battery to pin 3 of the RJ11 plug.
(USB) Red is +5v and black is ground
But from the image you attached (http://www2.jarnaker.com/wp/projects/chat-cord/IMG_4342.JPG), it seems that RED (+) is connected to the RJ11 and BLACK (-) is connected to the transformer instead.
Which is correct?
Thanks.
July 8th, 2005 at 7:22
# Nathan Says:
July 1st, 2005 at 19:18
Good job. i just had a question. would these be the required parts i would need:
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=281088
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=340724
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=428353
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=341609
hey the resistors you named in one of those links are not the right ones, just got them in the mail today, they are huge!, they are the 10w and there suppose to 1/2w, you can get atradio shack
July 8th, 2005 at 8:58
Patrick: You’re right. In the picture the polarity of the USB-voltage in inversed. But as said in post nr.3 the polarity doesn’t mather, this will work in both ways.
Just for simplicity it is said that the + should be connected to the transformer, otherwhise everybody would be asking the same question as you did
July 8th, 2005 at 10:08
Mr Blond: Great! Thanks for the prompt clarification..this would be my weekend hobby project
July 8th, 2005 at 18:11
Had no luck in find a 600:600 centre tapped transformer locally. They did have a 500:500,
hm center tapped. Any thoughts on making that work? Having said that, I happened to have 2 600:600 non center tapped transformers from another unfinished project and constructed one use seperate transformers for each input and it appears to function properly as well.
July 8th, 2005 at 18:22
syberdave: Glad the parts worked for you, I might run to radio shack at lunch and get that transformer to try it out.
As long as both parties can hear each other, I think it would be just down to thee issue of frequency response.
Phones arent that great to start with but, the better frequency response you have, I would think the better everything would sound it would be. How is your sound quality compared to a regular phone or compared to skype with speakers/microphone?
The 600:600 transformer might come into play more with other phones that may be more picky, but who knows it may work just fine. ::shrug::
Not only do we need to implement ringing somehow, but on-hook/off-hook detection as well to hangup or pickup the call.
July 9th, 2005 at 1:02
Hey XCol, could we skip the 555 circuit and just use the ringtone
to generate a 50hz signal? That could be a 50hz-pulsed 18khz sound fed
right to the transformer from the notch filter. Maybe we’d still need an
op-amp but heck, I could live with that.
July 9th, 2005 at 17:20
confusedpc: how did you get two 600:600 transformer non-ct to work?
syberdave: the part you had is a 600 ohm to 8 ohm is it not? they have a #273-1374 which is a 1:1 but i need to know how confusedpc got his to work above
July 9th, 2005 at 17:29
i got mine semi working but there is a lot of crosstalk between them. my litmus test is that if i play a mp3 i should not pick up anything through the windows sound recorder. otherwise people will hear their own echo, so i’m curious how you got it to work with 2 600:600 non-ct.
July 9th, 2005 at 18:17
Mr Blond:
Got the parts & fixed up but hear a “drool” tone on my phone (even w/o connecting the mic/speaker to my laptop). After connecting everything up, there is 1 wire each from the mic & speaker which is not connected to anything. Is this correct? The ground of the mic/speaker are connected to the resistor which is connected to pin 2 of the transformer. The “other” wire of the mic/speaker is connected to 1 & 3 of the transformer. I’m using the USB cable to provide power and a 1/4 watt 150 ohm resistor. Any help is appreciated. Thanks!
July 9th, 2005 at 18:40
i really like to chat with people on line
July 9th, 2005 at 23:11
confusedpc:
Compared to phone and skype, it sounds fine. I have it connected to a cordless phone with a hands-free thing and I even listen to music on it. But when I used Skype, my mom complained that the sound quality was bad. But maybe that’s because it’s connected to someone in Taiwan and there may be latency.
I’m in the process of building a device that sends a ring signal, with the help of XCol’s instructions. I’ll publish a step-by-step howto with pictures when I get it done. (If it works, that is.)
I don’t expect to need on-hook/off-hook detection, as I plan to make a pickup/hangup controller. I’ll have a serial port thing that controls a relay that sets the phone line connected or disconnected.
And for the ring detection, I plan on just making my modem do that. It can detect rings, and as a bonus, it can read Caller ID.
I know that my hacks are dirty - 2 sound cards, 2 chat cord things, a ring sender, and my modem. And on the software side, I have a script that reads DTMF tones and responds accordingly, and I’ll have to write a Python script that controls Skype API so it can dial and stuff.
I use Linux, btw.
July 9th, 2005 at 23:18
The ring sender thing is coming out to be expensive. I’ve spent around $30 on it, including a pack of 500 resistors (which could last me years) and 2 relays (damn, these are expensive; but I need them to switch the phone circuit to the 100v line; damn, I bought a SPDT relay and I need a DPDT. Damn damn damn.) But it’s about $20 without that big pack of resistors.
I couldn’t find a 1:50 transformer like XCol said, but I found a 120VAC to 6VDC wall transformer and 1:20 should be enough, since I read that about 50VAC should be enough. It’s so hard to open the stupid plastic case without a saw. At least I had a power screwdriver.
July 9th, 2005 at 23:21
ehwhat:
I think I’m getting crosstalk, too. It’s really annoying. When I’m playing a MP3, the data gets sent back to the record slot and the DTMF reader sometimes picks up weird signals. If anyone finds out a way to get rid of it, It’d be great.
July 10th, 2005 at 7:47
Followup: 1k to 8 ohm transformer
I’ve had crosstalk problems (me playing a MP3 will feed garbage to the DTMF decoder) and I’ve always thought that it was my sound card’s fault - until I messed with every setting to no avail.
So yeah, I’m having CT problems just like #86. I feel stupid now. Sorry for suggesting the wrong thing.
But I did buy a 1:1 non-CT transformer. How do you do full duplex with it?
July 10th, 2005 at 20:44
Well, friday while at work i build the cord using syberdaves components(the radio shack transformer).
I borrowed headphones to use on my pc, and my coworker had the phone at his pc.
When he spoke it sounded fine. I didnt have a mic at my end so we were not able to test it the other way.
He called a friend on the phone and there were some problems with us hearing him and he mentioned an echo or someting..
waiting ont he 600:600 transformer to come in to build it with those parts, more later.
July 10th, 2005 at 21:43
By the way.
The modem that has the Atech ATS-127A transformer on it was an ISA card.
Wanted to mention it because the part has great frequency response.
The low end of the frequency range is lower than the 300hz on the other transformers…
May not matter much, except for those those wanting absolute best.
July 11th, 2005 at 12:49
Hi guys. I m really loving wat u are doing to help us with free calls.
can any of you give me step by step of how to make that chat-cord.
I have tried hard but i still can’t manage to do it.
What should it buy? from where? how to cellect them?
Please make it simple….
Take care guys!!! jeje UK
July 11th, 2005 at 13:09
hey!!! where are you guys. I can see that most of you got it already.
I wish you could direct me how to have fun with free calls.
I am stupid in electronics.
Come on tell me what 2 do step by step.
what to buy (technical names),how to set the up and so on.
Oh God…i m just crying of being to far behind!!!!
July 11th, 2005 at 13:11
Would this be a correct transformer to use?
http://www.eijlander.nl/article.php?group=899&id=203478
I’m not realy into EL, so I’m asking just to be sure
.
July 11th, 2005 at 13:15
Non-El: That is the one to get. Actually I think it is the same one as used in the pictures of this article…
July 11th, 2005 at 13:32
jupiter:
1) Buy the parts mentioned above.
2) Follow the instructions.
3) Plug it in.
and you could only make free calls to people over Skype. SkypeOut (PSTN) costs money.
July 11th, 2005 at 16:15
Any updates on the ring circuit?
Part numbers, diagrams, etc.
So far we need some resistors, an op amp, a 555 timer, and a potentiometer
This where Im starting to get a little lost. That wikipedia page is way to much for me.
July 11th, 2005 at 17:32
For the ringer, XCol gave me the following circuit: http://syberdave.net/dv/circuit.gif .
That would give a 100VAC signal on serial cue. Then, we’d need a way to switch it into the phone line. I’m thinking about using a relay.
I’m going to hold off the ringer until I get the echo problem fixed.
July 11th, 2005 at 19:27
Is there anyone who can tell which transformer to buy and where in the Netherlands?
I’ve searched on conrad.nl, but could not find it. I’d really like to know!
July 11th, 2005 at 19:39
Thank you
A few questions:
1. In reference to Q1 and Q2: Transistors? If so what kind.
2. On the Serial line in: what pin on the serial port?
3. I would like to use the idea mentioned in post 53 by XCol using the “notch filter” instead of a serial trigger. I assume that the serial line in would connect to the filter circuit from the description in 71.
Thanks for the contributions XCol and syberdave, this thing is going to rock.
July 11th, 2005 at 20:41
Hey, I just bought this 600P / 600S CT Trans,
http://catalogue.e-sonic.com/cgi-dev/part?manucode=195&partnum=101F
But it’s got 4 leads on either side? What up with that?
July 11th, 2005 at 21:09
Find pin 1, it looks like it may be marked with a white line.
pins 1 2 and 3 are for one side of the transformer pin 4 looks like it is not used.
Opposite side, pin 5(opposite of 1)
looks like it is not used so the other side of the transformer is using 6 7 and 8.
Ignore 4 and 5 I think.
July 11th, 2005 at 21:12
Sorry it looks like 5 is opposite of 4 instead of 1.
Still ignore 4 and 5 though, just note the locations and the pin assignment on the page.
July 12th, 2005 at 3:27
confusedpc:
(1) “Now, select a transistor type to use… You need darlington NPN type, so 2 BC517’s, BC618’s, TIP100, BC182…. there is a huge range that will work here. Find some that suit your budget, neither will be putting out much heat, but you dont want to use tiny units either!”
(2) I’m not sure yet. I’m going to stick a LED in random places and run I/O code to see which one can control what.
Anyway, I haven’t contributed anything - everything came from XCol. It’s just that I asked.
July 12th, 2005 at 14:39
Thanks,
Ok well, you went after the info and are building one and posting results so.. it still counts in my book.
Anyways, Ill add one of those transistors to my cart after checking them out a bit.
July 12th, 2005 at 16:21
Worked like a charm, thanks for the tips all, this trans worked perf,
http://catalogue.e-sonic.com/cgi-dev/part?manucode=195&partnum=101F
http://www.e-sonic.com/
Although $18 CAN is pricey, it is cheaper than ordering a $5 USD trans from the US. Can I remove the battery and use this to feed audio from my pc out into normal telephone calls? or record calls?
July 12th, 2005 at 17:15
syberdave,
Thank you for above reply.
Did you mean that if i decide to go for PSTN (skypeout), i would be
able to to call anynumber in the entire world? Do you really mean that?
I would love to spend on it.
Please help if you can!
July 12th, 2005 at 20:02
jupiter: yes that’s true. It costs roughly 1.7 eurocent per minute for every landline across the world (at least in most western countries). But watch it, it isn’t possible to be called…
July 12th, 2005 at 21:22
Jupiter: Have a look at this site http://www.voipbuster.com
They offer FREE phonecalls from your computer to landlines in many countries. How they manage to do this for free is a question to me, but I signed up (costs €1) and I’ve already called several friends in other countries for free.
July 13th, 2005 at 1:04
hey, great hack!
has anyone from the UK managed to source the relevent parts?
I can’t seem to find the transformer at Maplin?…
cheers for any advice
-roof
July 13th, 2005 at 2:41
jupiter: http://www.skype.com/products/skypeout/rates/all_rates.html ; there are the rates. It’s not too bad. I use it sometimes.
And yes, you _could_ get incoming calls with SkypeIN. IT’s like $10 for 3 months, which isn’t bad.
July 13th, 2005 at 17:37
Order online:
https://www.alliedelec.com/Cart/ProductDetail.asp?SKU=283-1120
https://www.alliedelec.com/Cart/ProductDetail.asp?SKU=863-0119
https://www.alliedelec.com/Cart/ProductDetail.asp?SKU=928-9020
I’ve got the other parts, or can grab from Radio Shack, otherwise these prices seem relatively good for anyone. Not sure on shipping yet.
July 19th, 2005 at 12:39
Well, here is the question again… Sorry for that..
Is this the right transformer?
There is also a datasheet on the page.
Thanx!
July 19th, 2005 at 15:02
Thanks for the link Carson, I ordered yesterday from allied electronics, shipping was only $6.36 (UPS Ground) to South Florida, USA. The only downside is that their website does not tell you the shipping cost when you checkout, it’s calculated afterwards and then sent to you via email. Seems like a good company, we keep everyone posted.
July 19th, 2005 at 22:05
So, I built this thing using thr bourns lm-np-1002 and I’m getting a god-awful hum on my phone. I’m using a wall-wart to supply the 9V instead of a battery. Also since i wanted to make sure it works it’s just jumpered together, not soldered. Any ideas on how to get rid of the hum?
July 19th, 2005 at 23:07
shitaka: Your problem is most probably the power source. Try to use a battery instead and see if it goes away.
A regular ac/dc adapter will only provide a somewhat clean current if you put it under a load, but that won’t work in this circuit.
July 20th, 2005 at 3:35
This can be used with voipbuster.com right?
July 20th, 2005 at 21:51
Hello,
Is it possible to use the same phone to skype and telephone line ?
July 21st, 2005 at 1:10
Hi,
Nice and simple circuit, tutorial is good enough (kinda like my hd44780 lcd hack http://nerdhero.org/index.php/Howtos/LcdDisplay ). And liked the idea on getting the ring signal with right frequency on the line out to electronically switch different circuit for ringing (post 53 Xcol).
Was thinking of different switch, mainly switching between landline (PSTN) or skype. Imagine you have your cordless phone hooked up, sometimes you want to use the landline (maybe when pc is switched off or your inet connection is gone or whatever) and other times you want skype.
Would it be possible for instance to make the key ‘#’ or #+some digit sequence on the phone trigger a switch.
This way I could do something like #1 12345 -> calls 12345 on skype and
#2 12345 -> calls 12345 on regular line.
Ofcourse meaning hooking this box up to phone line + pc. This is in essance the same kind of circuitry but then catching a sound frequency from the phone output instead of the line out.
Actually the switching idea kinda already exists and is for sale here : http://www.dualphone.net/ but I will have same problem getting it in my country and/or probably high price tag…
Ow yeah and some people ramble here on using a modem to do this instead of building the circuit. Don’t really get the point of it (like post 40). All a modem does is do analogue/digital transformations to send data over phone line. Don’t see how it’s gonna help you talk on skype. Only thing an old modem is good for is ripping out the 600/600 transformer
. Ah ok, sorry, he’s talking about a voice modem euhm nevermind this paragraph then hehe
Anyway, happy hacking … hope to see some of you at What The Hack 2005!
)
This is where we plan to get the homebrew chat-cord working under linux (so rewriting the software in linux to capture the phone key sounds from /dev/dsp will be fun
July 22nd, 2005 at 4:40
I have already finished the DIY chat-cord,works perfectly, excpet, people will hear they ECHO after 1 or 2 sec, I checked every single wired, No short at all, also I’m musing 600:600 Ohm Center Taped Transformer…
Anyone has this problem???? how do you solve it?
Thank you!
July 22nd, 2005 at 7:52
Alex: try turning down your volume. Make sure your microphone is muted in the playback part of the volume controls, but select it in the recording section. It will probably be crosstalk sent back to the other side.
July 22nd, 2005 at 8:39
Hi Mr Blond, I have try to miniaisze my voice & mic volume, also disalbe +20db and muted the playback part of volume control,
people can still hear the ECHO very clear (delay few seconds), i try to disable “center tape part” and attach the “center tape” make no difference, wondering any body else has same problem?
Thanks
July 22nd, 2005 at 9:27
you could configure skype to ring the pc speaker, in tools–> options, that way you dont have to depend on your sound card
July 23rd, 2005 at 5:05
Hi, this is an awesome write up. I have only a basic (very basic) understanding of how this works, and am working on soldering one together myself. After visiting radio shack and finding most of the parts as described, the transformer only has 4 leads, but is 1:1. Getting confused by it, I de-soldered a transformer off of an old pci asustek modem, which I think will do the trick, assuming (properly I hope) that this is the transformer, but it only has 5 leads on it. Any suggestions? The transformer is labeled LB-2943-CT Link Com 9911 . Google turned up nothing matching this string, so if anyone knows if this is right, it would be appreciated.
July 23rd, 2005 at 8:45
@Non-EL: That trannie found at eijlander.nl is the one to get (read mr. blond’s response).
).
I am about to order a few (shipping costs are a bit high
Let me know if you need one too, we might be able to work something out.
Franc.
July 23rd, 2005 at 16:02
@Franc: I’m not sure if I’m going to order it. I have two old modems that also contain 1:1 transformers (well contained actually
. I think I give those a try first.
But thanks for giving me the opportunity!
(Still wondering if the conrad transformer with order#: 516686-8B is the right one (www.conrad.nl). They give a 10 euro discount now :p)
July 23rd, 2005 at 16:30
Nen-EL: The conrad transformer you mentioned is NOT the right one, it is not center tapped…
July 23rd, 2005 at 16:33
Rick: If your transformer has 5 leads use the side which has 3 wires as secondary side (to the pc) and the side with 2 wires as primary(to the phone). Actually you have found a transformer that is perfectly suited for this application, while I (and many other…) used one which was center tapped at both sides (6 leads), which is not necesarry…
July 23rd, 2005 at 18:14
Mmmm…. I thought about using something from an old modem too, but there’s nothing on there that seems to be center tapped.
Would any old phone have a tranny that could do the job??
July 23rd, 2005 at 19:51
mr.blond: Any idea on the pin configuration, at least in regards to the instructions? It’s a bit daunting, as looking at it, wit hthe two pins facing me, I beleive pin 1 to be at the bottom right corner, since there is a rather large bump there, which I would assume is supposed to be pin one. Anothr problem with it is, on the 3 pin side, the middle pin has a 3 embossed above it, which is making me really question which lead is which. My site is down currently so I can’t post a pic, but owuld be more than happy to share some photos of the modems I ripped this off of as well as of the transformer itself. cyberwormatgmail if you’d like to see and offer up some friendly advice. (to be shared on here once we know what’s up with this thingy)
cheers
July 24th, 2005 at 14:48
Mr blond
There is one thing i still not understand. we,ve been talking about
how to build a chart cord. What about buying it? Does it cost too much?
Will i only communicate over IP with only a chat cord OR i will need it
for skype out?
Suppose that i buy it or i manage to build it. willi still have to pay some
money for calls (PSTN).
Thanks.
July 26th, 2005 at 3:19
Hi just finished my chat cord.
Works perfectly in windows xp but I also had to turn volume down to get rid of echoes.
Also not all phones work, I tested 3 and 1 did not work.
Having that said, found all parts here in little belgium for about 9 euro at http://www.rato.be
Here are some pics of my version : http://walle.nerdhero.org/chatcord/ .
I also used an extra adsl splitter box as housing so mine looks surprisingly similar except had to resort to sticky tape to keep it together because did not have any glue lying around
.
July 26th, 2005 at 9:53
@jupiter and others: I think a lot of you guys don’t understand what this thing does or how skype works…
All Skype (or MSN Messenger or whatever) does is make Voice connection to someone else. This can be another Skype user (which is free) or a real telephone (which costs money).
This is true no matter how you use Skype. Whether you plug in a headset, use a separate microphone and speakers, or whatever.
Same goes for the original design of the wireless phone where you search for audio in and out and connect it to your computer’s soundcard.
All you do is use the real telephones microphone and speakers to use as an extension of your computer’s soundcard.
Does not change functionality of Skype, doesnot cost any money.
What the chat cord does, is make it possible to attach any phone to your PC’s soundcard by ‘translating’ real phone sounds and beeps into sounds that your PC’s soundcard understands and vice versa.
With the added advantage that, with the help of a small piece of software, you can even press the buttons on your phone and really ‘dial’ a number. This is something that doesn’t work in the original design, because the phone isn’t really ‘working’. You’re only using the mic and speaker there.
So using the chat cord is still free when you call another skype user and costs money when you dial a real phone.
Simple.
Now all you gotta do is find the right transformer to build one
July 27th, 2005 at 21:12
thanks for this informations, i couldnot find the same transformer in local market and i found
the transformer from my old fax. and i made it very easily and working very smoothly
now i want to dial manually my regular another one phone and want to connect this voice in to that
SKYPE phone(chatcord) >>>>>>>>>> my regular phone >>>>>>>>>>> my friends regular phone
is that possible, any methode this voice in and out to map a regular phone
July 28th, 2005 at 16:04
Rick:
Your transformer will either have 3 pins on one side and two on the other, or 3 pins on both sides. The exact pins that you use don’t actually matter, so long as you use the pins the right way.
If yours has 2 on one side, label one of the end pins on the side with 3 pins as pin 1 and go from there. If your transformer has 3 pins on each side, do the same, but ignore the middle pin on the other side.
Mr. Blonde only put in the numbering to make it easier to reference the diagram. It’s not like an integrated circuit or something.
July 28th, 2005 at 19:35
Bob/Paul:
Thanks. That makes things a bit clearer. I guess now the only thing that I’m not sure about, is where the power goes, and where the shielding goes. In this writeup pin 6 is referenced as a power lead, but when there’s only 5 pins, what then? Do I run the power inline with the signal from the phone side, or the line in/out side? Forgive my lack of experience at this. It’s the circuitry that is confusing me more than the whole concept of how the device itself works. I;d have it done in five minutes if I could find the same parts as the author.
July 28th, 2005 at 22:13
Wicked Mr.Blond,
the BCO is proud of you ultimately wide deed.
Restecp!
July 28th, 2005 at 23:45
Something I’d like to share with you guys, is a pretty decent use for this, that I thought up. I work for a small business, that has 5 offices spread out across our area. We daily make many many long distance calls inter-office. I plan on using this “chat-cord” to plug into our current telephones (we have two lines, but use 4 line telephone sets) as a third line. The point being, that once in place, for inter-office calling, we’ll be using our existing phones and internet connection to call inter-office and cutting our local long distance calling down to practically nothing. Hope this idea comes in handy for others too.
July 30th, 2005 at 11:16
rick how you will plan to connect pots with this ….
July 31st, 2005 at 9:16
rafee: by simply plugging the chat cord phone line into an empty line 3 terminal on the telephone handset. So it will actually be working in paralell with the POTS system, basically partitioning inter office calls from external calls. The phones we use are AT&T model 955
August 3rd, 2005 at 4:10
hi guys.. can anyone help me please?
here is the caralog. https://www.alliedelec.com/catalog/catalogpages/200405/697.pdf
is there any of these 928-7615 928-9020 928-9024 that will not work?
thanks!!!!!!
August 4th, 2005 at 9:25
Bruno: Both the 928-7615 and the 928-9024 will work. The 928-9020 will NOT WORK since it is not center tapped.
August 5th, 2005 at 0:39
As promised in post 122 I was gonna make a linux app for the chat-cord to interface with skype @ What The Hack.
).
Well I did not get to work much during What The Hack (those who were there know that there was plenty of other stuff to do
Here are some screenshots:
http://walle.nerdhero.org/chatcord-api/chatcord-linux4.jpg
and
http://walle.nerdhero.org/chatcord-api/chatcord-linux5.jpg
Okay, so it does DTMF detection and sends the keys to skype (yep still a little bug because 0 is sent as + ).
But you can see it is almost finished dudes, anyone interested?
August 6th, 2005 at 16:46
Just wanted to drop a note and say I finally built my chatcord. I also added a switch so you can direct audio to the phone or my PC speakers without any effort. Check it out at http://markfalvo.com/?$wID=6
August 7th, 2005 at 11:13
Marco: Neat! Very nice.
August 8th, 2005 at 14:10
Hello walle,
I’m interested in Linux version…
Will you publish it ??
August 11th, 2005 at 5:47
Dude, this could be used to run a cordless 56k modem. Plug into the handsfree jack of a phone.
August 12th, 2005 at 12:40
What about echo cancellation?
How to remove echo on the other side?
Any hints?
August 12th, 2005 at 19:22
For the linux version go here http://walle.nerdhero.org/chatcord-api/
.
(binary only and will expire in 30 days or so) reason: still negotiating with CEO from chat-cord about the software
I plan on making a Mac OS X version of the dialler as well by the way…
August 14th, 2005 at 6:17
Dear VoIP Confused:
A modem card only receive a phone line (FXO), it acts like phone terminal. We need generate a FXO to talk a phone terminal. No confuse when modem card switchs Phone Line (LINE), by a relay on second RJ11, to Phone terminal(PHONE).
August 22nd, 2005 at 21:14
Does anyone have a complete RadioShack parts list?
Thanks in advance,
Chris
August 24th, 2005 at 2:04
Yeah, where is the Radio Shack parts list? i thought I saw it here a week ago?
September 11th, 2005 at 18:57
hi!The transformer I bought to build my chat-cord din´t seem to work,
so kinda fooling around I connected one cable of the RJ11 to the speakers
cables and the other to the mic cable and it worked(I left the ground
cables alone). Does this put my computer in risk?
September 13th, 2005 at 13:24
I’m still looking for transformator here in sweden. Found something in ELFA today but does not really know if it will work. Is this the part i need http://www.elfa.se/elfa-bin/setpage.pl?http://www.elfa.se/elfa-bin/dyndok.pl?lang=en&dok=2001284.htm
September 15th, 2005 at 5:56
So has any one tried the 2 non center tapped transformers, I cant find one here in australia.
I would think you could just link two in parallel on the primary side and in series on the secondry side. or will this make the phone see 300 Ohms?
September 15th, 2005 at 11:11
Snoble, I have tried it and it makes the input impedance 300 Ohm indeed. It worked with an old wired phone but my wireless digital DECT phone didn’t work with it. I think it is more picky on its input impedance. But it is worth the try. When it doesn’t work you might try putting a 300Ohm resistor in series at the input. It will lower the volume but it might work.
September 19th, 2005 at 1:03
Still can anybody help me finding the transformator here in sweden? Please…!
September 19th, 2005 at 12:29
After a long search I was wondering if this transformer will do the job: http://www.oep.co.uk/surface_mount_line_isolation_transformers/
surface_mount_line_isolation_transformers.html
If it isn’t appropiate and someone in Spain knows where to get it please, tell me!
September 19th, 2005 at 22:47
My other comment was wrong, I think the good one is this: http://www.oep.co.uk/audio_transformers/miniature_encapsulated_input.html
September 21st, 2005 at 4:44
The chatcord parts can be found in virtually any computer modem card, just find/buy an old surplus one and cannibalize the parts from the circuit board. As well, cordless phones have come down a lot in price and converting one to a chatcordphone (all-in-one) is probably the best route to go. Use a 900 MHz or 5.2 GHz cordless phone to eliminate interference with WiFi.
September 22nd, 2005 at 10:22
Dear,
It would be helpful any way, even though I have not red yet.
Syncerelly,
Mike
September 24th, 2005 at 2:34
I placed this two weeks ago:
hi!The transformer I bought to build my chat-cord didn´t seem to work,
so kinda fooling around I connected one cable of the RJ11 to the speakers
cables and the other to the mic cable and it worked!!(I left the ground
cables alone). Does this put my computer in risk?
Could somebody reply pls!
September 24th, 2005 at 14:01
What do i do if my transformer only have 4 pins?
September 25th, 2005 at 20:07
Ik heb de simpele oplossing voor draadloos skypen.
doe het zelfde als onze chris, alleen gebruik ik de intercom functie van de draadloze telefoon.
neem de ingang (mic) van je basis station en neem de speaker uitgang van je bassis station en daarmee heb je de in en uitgang
van je draadloze telefoon!!! het enige dat je dan nog wel moet doen is; als je iemand wil bellen dan moet je dit activeren via je computer maar daarna kun je vrij rond lopen in je huis. Ook als je gebelt wordt moet je dat via de computer activeren en daarna kun je dan ook vrij rond lopen.
Dit is alleen leuk als je niet te lang wilt zoeken naar de in en uitgang op de printplaat en voor de niet technische mensen onder ons.
Als ik nu skype-bel dan kan ik lekker rond lopen.
September 26th, 2005 at 8:40
hey~ I just found micro mini transformer that looks like the one for this project… can anyone tell me its the right one? [http://www.stancor.com/pdfs/pg43_44.pdf](PCT-77) thanks~~ and good luck for those who already got the parts~~
September 26th, 2005 at 8:45
oh.. i just missed one.. sorry.. its another one~
http://www.stancor.com/pdfs/pg37_39.pdf (TTPC-6) - 1319589 (order number, you have to ring them as its located US but they will get this without charge)
http://www.stancor.com/pdfs/pg43_44.pdf (PCT-77) - 1018668 (order number, you have to ring them as its located US but they will get this without charge)
please reply me if its ok for this.. and oh… its from farnell you can order those ~~ farnell is international so they did not charge me for transfering the stock from US to AU~~ just standard shipping~ just to let you know~~
thanks~
September 26th, 2005 at 20:10
Icep: Have a look at Elfa again, http://www.elfa.se/elfa-bin/dyndok.pl?lang=se&vat=0&dok=187904.htm The second one ( 56-661-02 ) on that page should do it. It’s 171sek or about €19, so it’s not the cheapest, but it should work.
September 27th, 2005 at 20:53
Dear all, you do not need to use a transformer. I have just read this project and the problems to get a transformer, so I assembled a resistor bridge and it works fine with my ALPHA 1800 CTA. 3 resistors, 2 caps, 1 battery. I will upload the sch somewere.
September 27th, 2005 at 21:12
So this is here http://www.szundibundi.fw.hu/phone.jpg
Works fine. I start to make a very simple circuit to transfer ringing to phone as well.
September 27th, 2005 at 22:10
Call a friend and adjust the pot for best performance. Good luck!
October 9th, 2005 at 4:54
PLEASE ANSWER ME!!!THIS IS THE 3RD TIME I`M PUTTING THIS
The transformer I bought to build my chat-cord didn´t seem to work,
so kinda fooling around I connected one cable of the RJ11 to the speakers
cables and the other to the mic cable and it worked!!(I left the ground
cables alone). Does this put my computer in risk?
October 11th, 2005 at 4:40
for snoble (re his message #158)
if you have read silicon chip magazine
for september 2005, you will know this
already, but if not Altronics has
600:600 ohm xformers centre-tapped on
the secondary
October 12th, 2005 at 2:05
I want to know if you could send me all the inventions and instructions for those inventions. Please let me know.
thank-you
l-master
October 12th, 2005 at 10:44
l-master: Drop me an email at contact1 @ grynx.com
October 12th, 2005 at 13:39
There is a possibility that if you have a transformer without a center tap, you could possibly use two resisters
o—(R1)—o—(R2)—o
^TransPost ^CntrTap ^To Trans.Post
The center junction of both transistors could act as a center tap. You will have to experiment with different values for the resistors, but both resistors have to be the exact same values.
Good luck with your project.
October 12th, 2005 at 13:44
There is a possibility that if you have a transformer without a center tap, you could possibly use two resisters
o—(R1)—o—(R2)—o
^TransPost ^CntrTap ^To Trans.Post
The center junction of both resistors could act as a center tap. You will have to experiment with different values for the resistors, but both resistors have to be the e