On Fri, 13 Jul 2007 19:45:44 +0100,  "Ron Jones"
<[EMAIL PROTECTED]> wrote:


>
>50V IIRC.  Also with Broadband the bell wire (No.3) is superfluous.  The 
>lines coming in from BT, go to 2 and 5.  In the master scocket there's a bit 
>of circuitry to make the bell signal on line 3.  The microfilter does not 
>use line 3 at all.  Each one has it's own "No.3 generator" for the phone 
>outlet socket built into it.  So if you have your extensions wired up with 
>lines 2, 3, and 5 - then you actually add more noise to the line as the 
>third wire acts like an aerial.  I disconnected line 3 and got a 30% speed 
>increase.
>


Oh dear - going back many years now - but yes about  50V - but
constant current source ??


I was more telegraphy rather than telephony - and on our telegraphy
circuits we used 20mA loops with + and - 50 Volts for the telex
circuits - and then we converted it to radio to communicate with
overseas, ships and oil rigs. (:-))

Almost back on topic !!!


-- 

Malcolm

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