home made chat cord?

[[email protected]]

Any moidification required for UK phone useage?

http://www.vital.pri.ee/PSTN/

Thanks

Adam

 

[Jasen Betts]

Any moidification required for UK phone useage?

http://www.vital.pri.ee/PSTN/

BT phone plugs use pin 2 and 5 instead of 3 and 4 on RJ 11
whatever you do it will not ring your phone.

the "USB powered" version will not work.

the bottom version looks to be the best of the three

the circuit looks harmless.

no guarantes on how well the called party will be able to hear you
itsm they'll mostly be hearing their own voice delayed
by the internet lag.

If you call someone else who has the same setup you may end up
listening to a repeating echo.

Bye.
Jasen

 

[Adam Aglionby]

BT phone plugs use pin 2 and 5 instead of 3 and 4 on RJ 11
whatever you do it will not ring your phone.

Most phones , or cordless handets go rj11 with centre 2 pins, thanks
for the lookout though.

Telephone signalling not my strong point , but guessed there must be a
catch , something to do with UK 3 wire and bellringer capacitor as well
guess.

the "USB powered" version will not work.

Spotted that one , there isn`t -5V on USB so no way is -5 and +5 going
to give you the +9V need for off hook status.

the bottom version looks to be the best of the three

the circuit looks harmless.

Well on that advice had to try it

no guarantes on how well the called party will be able to hear you
itsm they'll mostly be hearing their own voice delayed
by the internet lag.

And you spotted that one, test subject binatone cordless, circuit built
used 2.2uF rather than 3.3uF , because was all had to hand.

Didn`t manage to try out chat cord software because needs XP , test PC
running ME, using
https://www.voiptalk.org/products/really_useful_signup.php,not an
affiliate link just a free UK geo number, running on Xlite, works very
well with a headest, works, kind of, with the adapted binatone.

As you anticipated , tests to mobile phone from binatone>adpapter>PC
resulted in a loud delayed echo being delivered back to the mobile,
call clarity on the binatone was fine.

Some twiddlling with mic gain did appear to make some differnce, but
also wondering on other factors, wonder if chat cord software has any
form of echo cancellation built in, main feature appears to be to
recognise DTMF tones from keypad.Will try adapter on XP installed
machine.

Is the substitution of capacitor value critical?

Would a transformer balanced solution be any better?

http://www.grynx.com/index.php/projects/build-your-own-chat-cord/

If you call someone else who has the same setup you may end up
listening to a repeating echo.

Bye.
Jasen

Help much appreciated.
Thanks
Adam

 

[Adam Aglionby]

Most phones , or cordless handets go rj11 with centre 2 pins, thanks
for the lookout though.

Should have been centre pinned RJ11 lead at phone end as in plugs into
phone body

and

https://www.voiptalk.org/products/really_useful_signup.php

probably works better

Its late , the flux fumes got to me.

Thanks
Adam

 

[Jasen Betts]

Most phones , or cordless handets go rj11 with centre 2 pins, thanks
for the lookout though.

Telephone signalling not my strong point , but guessed there must be a
catch , something to do with UK 3 wire and bellringer capacitor as well
guess.

no. voltages, it takes around 45V (25Hz AC) to ring a phone.

Spotted that one , there isn`t -5V on USB so no way is -5 and +5 going
to give you the +9V need for off hook status.

also the 0V may be connected to the common terminal of the speaker output.

Well on that advice had to try it


And you spotted that one, test subject binatone cordless, circuit built
used 2.2uF rather than 3.3uF , because was all had to hand.

Didn`t manage to try out chat cord software because needs XP , test PC
running ME, using
https://www.voiptalk.org/products/really_useful_signup.php,not an
affiliate link just a free UK geo number, running on Xlite, works very
well with a headest, works, kind of, with the adapted binatone.

As you anticipated , tests to mobile phone from binatone>adpapter>PC
resulted in a loud delayed echo being delivered back to the mobile,
call clarity on the binatone was fine.

Some twiddlling with mic gain did appear to make some differnce, but
also wondering on other factors, wonder if chat cord software has any
form of echo cancellation built in, main feature appears to be to
recognise DTMF tones from keypad.Will try adapter on XP installed
machine.

Is the substitution of capacitor value critical?

I can't be sure. but AFAIK electrolytic capacitors often aren't precision
devices. what's needed is a way to stop the signal that comes out of the
speaker jack from going into the microphone jack but still allowing the mic
to get the speach from the phone.

Would a transformer balanced solution be any better?

yes I expect it would help a lot. maybe something like this

100u 9-12 V
+|| | | | +
---||---+---||||||-----+
SPK || | | | | |
-+ | |
| | `--
| / phone
| \echo cancel .--
| 100R/ |
| \<---. |
| / | |
| | | |
+------+------[100R]--+
| |
____ _------+ |
_)||(_ |
MIC _)||(_ |
____)||(_ |
~---------------'

600:600 audio line transformer

you should ba able get rid of most of the echo by adjusting the cancel pot
you may get further improvement by putting capaitors in there
(but i'm not sure where or what size)

http://www.grynx.com/index.php/projects/build-your-own-chat-cord/

that one looks like it may suffer from the same problem.
if the 150 was swapped for a variable resistor it could help.