Treggers,
Let's assume that TBR21 goes through and becomes a CTR. Hooray we
exclaim! Our complicated, busy lives have become so much simpler! We
just design one Euro DAA with a simple ringer, easy to implement AC
characteristics, and the minor inconvenience of a 55mA (+/-5) current
limit on it DC characteristics curve. Problem solved?
You guessed it! As soon as one problem is solved, there's always a
new one to replace it!
What I'd like to get a feel for is this:
There are a fair few PABX systems out there on the market that feed
the TE (i.e telephones / DAAs) connected to them via a transistorised
current source, not via a good old battery, resistor and Off Hook
detect relay.
I heard one colleague changed his French DAA current limiter from
45mA (i.e right in the middle of the range of values (26-60mA) that
France requires you to perform your current limiting for NET4) to
55mA (i.e dangerously close to the high end of the scale using low
tolerance components), because some PABXs tried to force >45mA into
this DAA and therefore wouldn't work (No Off-hook detect).
DOES ANYONE HAVE ANY SCARE STORIES TO TELL ABOUT PABXs THAT TRY TO
FORCE >55mA INTO EXTENSION LINES CONNECTED TO THEM?
Thanks in advance - John Dunn
************************************************************
-------------------------------------------------------
The comments and opinions stated herein are mine alone,
and do not reflect those of my employer.
-------------------------------------------------------
************************************************************
