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Forum: µC & Digital Electronics Interesting experiments with ADSL splitter


Author: Thinh Nghiem (thinhnghiem)
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As we know, the ADSL splitter box has 1 input and 2 outputs, one for 
phone signal line, and the other for internet signal line
I have executed many experiments with this device, and some give out 
interesting results. I list here 5 of them. Their schemas can be found 
in the attached screenshot
Experiment a)
Plug the telecommunication line into the input. Then in the output 
lines, I make the swapping. I plug the phone line to the internet 
output, and the internet line to the phone output
Then I dial the phone to call to a fax number
Surprisingly, I heard the busy tone, instead of fax tone.
Note: When I connect in normal way, plug the phone line to the phone 
output, and internet line to the internet output, this effect does not 
happen. That means I heard the fax tone as usual
Experiment b)
I make the looping back from the net output to the input. To do this, I 
cut into the cable and heal the wire inside, with the same color 
correspondingly (green to green, red to red)
Then, I connect phone output to a telephone machine.
Result: No tone heard when I picked up the phone machine

Experiment c)
I make the connection between phone output and net output, by cutting 
into the cable and healing the wire inside, with the same color 
correspondingly (green to green, red to red), similarity as I did in 
experiment b)
Then, I connect phone output to a telephone machine.
Result: No tone heard when I picked up the phone machine

Experiment d)
Wall line is plugged into the net output (Not the input). Then, I make 
the looping back from the phone output to the input. To do this, I cut 
into the cable and heal the wire inside, with the reverse color 
correspondingly (green to red, red to green)
Then, I connect input line to a telephone machine.
Result: No tone heard when I picked up the phone machine
Note: If I repeat the same experiment by healing the wire with the same 
color correspondingly (green to green, red to red), no issue happens. 
The tone can be heard from the phone machine
Experiment e)
Wall line is plugged into the phone output (Not the input). Then, I make 
the looping back from the net output to the input. To do this, I cut 
into the cable and heal the wire inside, with the same color 
correspondingly (green to green, red to red)
Then, I connect input line to a modem to emit Internet signal
Result: No internet signal is created

Author: Easylife (Guest)
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Did you also try to throw the splitter out of the window from 3rd floor, 
heal the housing with duct tape, connect it to a TV input and look what 
kind of picture you see.
Could be interesting, try it, I would be interested to hear about the 
results.

Author: matzetronics (Guest)
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Hmm, still looking for any question in this posting. For your info - 
this all is not really surprising.
The Splitter basically consists of a highpass for the DSL Signal and a 
lowpass for the telephone line.
Sometimes the DSL output is simply wired to the input as most DSL input 
circuitries in Modems provide the highpass themselves. Teardown a 
splitter and extract the circuit, its a really simple thing. I have 
built a splitter myself when the guys forgot to send me one and it 
simply consisted of two coils in the a/b lines and a condenser for the 
telephone - worked perfectly.

Author: trolley (Guest)
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matzetronics wrote:
> splitter and extract the circuit, its a really simple thing. I have
> built a splitter myself ...
... after doing your experiment, Easylife.

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