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ADSL modem connection

J

J M Noeding

Jan 1, 1970
0
Does somebody know which pins on the RJ45 connectors are connected
between the modem and ISDN-filter. It is some problems in this area
with lightening and I wish to use a transformer which stands at least
40kV and I have good experience with for HDB3 line code. Suppose the
band is 200-1000kHz

Jan-Martin
LA8AK, http://home.online.no/~la8ak/d.htm
 
J

Joerg

Jan 1, 1970
0
Hi Jan-Martin,

DSL and an ISDN filter? Anyway, in the US it usually connects to the
center pin pair. But the company that supplies DSL in your area should
be able to tell.

Also, with the modem unplugged you should be able to measure the signals
differentially on the cable that is connected to the modem as it tries
to synchronize to the disconnected line.

Regards, Joerg
 
J

J M Noeding

Jan 1, 1970
0
Hi Jan-Martin,

DSL and an ISDN filter? Anyway, in the US it usually connects to the
center pin pair. But the company that supplies DSL in your area should
be able to tell.

Also, with the modem unplugged you should be able to measure the signals
differentially on the cable that is connected to the modem as it tries
to synchronize to the disconnected line.

Regards, Joerg

thanks,

forgot to mention the modem, it is Zyxel Prestige 600 series,
on the page http://www.noding.com/la8ak/12345/n11.htm is shown some
variety of transformers tested, and the simple type which substands
40kV is easily found

Jan-Martin
 
J

Joerg

Jan 1, 1970
0
Hi Jan-Martin,

Nicely wound toroids. I'd just be careful with 40KV. Even a Teflon
coated wire with about a millimeter of insulation thickness is usually
not rated nearly as high.

In medical electronics you have to certify all components in the "strike
path" to withstand a certain voltage. In our case mostly about 5KV
because that is the charged-up voltage of a defibrillator. Believe me,
if you need to transfer sensitive signals it is very tough to create an
isolation that holds this voltage level safely for extended periods and
will be blessed by the agencies. The latter is the hardest part :)

Regards, Joerg
 
J

J M Noeding

Jan 1, 1970
0
Hi Jan-Martin,

Nicely wound toroids. I'd just be careful with 40KV. Even a Teflon
coated wire with about a millimeter of insulation thickness is usually
not rated nearly as high.

In medical electronics you have to certify all components in the "strike
path" to withstand a certain voltage. In our case mostly about 5KV
because that is the charged-up voltage of a defibrillator. Believe me,
if you need to transfer sensitive signals it is very tough to create an
isolation that holds this voltage level safely for extended periods and
will be blessed by the agencies. The latter is the hardest part :)

Regards, Joerg

Joerg

Well, I had some particular projects at work at Norwegian telecomm and
was working on some ideas to protect the telecommunication equipment,
and in many instances it worked out with very little sync-loss
compared with doing nothing. In one instance I reduced 5000
sync-losses in 24 hours to 3 bit-losses in 4 days.
Anyway, it has been some work on lightening, and in telephone lines on
cables it is unlikely that lightening voltages are higher than 35kV,
but the limit for our test equipment was 40kV, so we didn't know what
the transformers could stand.

I agree with the points you mention, but the normal line transformers
- wound with magnet wire and no steps are taken to avoid damage if
stuck by lightening breaks down somewhere around 4-5kV, so the
addition of an extra transformer you believe stands 40kV might be an
improvement, but in some cases it don't.

In our case, we solved some equipment and made many customers happy -
at least the error bits and sync-losses were minimized

Jan-Martin
http://www.noding.com/la8ak/12345/n11.htm
 

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