DIY DECT COMS

[henny]

since reading a post some weeks back I relation to interfacing a DECT cordless phone to talk back , I've been thinking.

 

useing the following pages for reference in theory the below may be true.

 

http://www.dmx512.com/web/comms/tecpro/tptech.htm

http://www.hut.fi/Misc/Electronics/circuit...einterface.html

http://www.wppltd.demon.co.uk/WPP/Wiring/U..._telephone.html

 

 

line lead

from dect 3 pin XLR

base station (coms line)

 

HOT pin 5 --------------------------- Pin3 SIGINAL

 

 

COLD pin 2 --------------------------- Pin1 GROUND

 

in theory (this is all theory at the moment) with any look coms should get audio from the handset and vice verser.

 

(note this will defentley not work on systems that need power from the phone line , eg a normal phone, but as a cordless pulls its power from its own psu theres a chace)

 

don't hold me to any of the above, it was one of them ideas that came to me from no where coupled with a 10min goggle .

 

so I'm going to have a play in the workshop when I get back to work tomorrow.

 

will report back

 

if any one else has tried anything along the lines of this please advise on what you came up with.

 

thanks

 

henny

[computer]

I've written basic firmware for the PICAXE chips that acts basically as a 2 way modem. Since these send out audio tones, plugging these into the headset jacks or soldering onto the actual mic/speaker in a handset would be able to have 2 way comms wirelessly and cheaply. Seeing these 'modems' send a third pin high to initiate the communications, a few pins could be connected to the buttons on the front of the phone, so when it got turned on it could automatically 'press' the buttons in the correct order to start an intercom session. Likewise an interrupt on the sound input to the base PICAXE could detect it ringing, and pick up the intercom. Some DMX interfacing either way would let you do one way wireless DMX. A bit more electro-magic and you could have 2 way comms with signal and error checking and perhaps cryptos to prevent hacking too.

 

I hope that is similar to what you're thinking. I don't understand your idea though... How would connecting the DMX line to the telephone socket on the base station generate DMX? Remember not to plug modified communication equipment into a UK phone line or you could get into trouble with BT.

 

computer

 

[edit]

poop! just read your post again and realise what you mean, you mean techpro cans system rather than DMX. argh! oh well, just ignore me :unsure:

[/edit]

[IanG]

A friend of mine has done this, but from the headset jack of a comms pack rather than the line. It's easier that way as there is no superimposed call DC and the sidetone rejection functionality is already built into the comms pack.

[henny]

I was thinking of doing it that way if my origrinal idea failed.

 

I was thinking that the superimposed call dc would not up set it because they can handel 48V dc to power normal phones

 

henny

 

 

A friend of mine has done this, but from the headset jack of a comms pack rather than the line. It's easier that way as there is no superimposed call DC and the sidetone rejection functionality is already built into the comms pack.

<{POST_SNAPBACK}>

[Ellis]

A friend of mine has done this, but from the headset jack of a comms pack rather than the line. It's easier that way as there is no superimposed call DC and the sidetone rejection functionality is already built into the comms pack.

<{POST_SNAPBACK}>

 

The DC element can be lost easily by the use of a suitable capacitor in the line. The DECT telephone itself will have side-tone rejection - the tecpro units just use a telephone wheatstone bridge circuit with a little imbalance to give you the side-tone.