[time-nuts] ADSL in UK was Thunderbolt SMPS question OT

Robert Atkinson robert8rpi at yahoo.co.uk
Thu Jul 18 13:53:04 EDT 2013


Hi Chris,
It is very likely that the cause of interference pick-up (not the actual source) is BT's odd wiring scheme. The extensions use a third wire for the ringing signal. This unbalances the wiring making pick-up more likely on extensions. The ringing signal is basically just the incomming line "B" DC blicked with a 1.8uF capacitor. This is only required for old phones with mechanical ringers. Try disconnecting the ring wire at the master socket. It's connected to terminal 3 and should be Orange with White bands. Leave just terminals 2 and 5 (Blue with White bands and White with bands) connected to the extension sockets. Even if you are not having trouble this will often produce a substantial increase in speed. See http://www.wppltd.demon.co.uk/WPP/Wiring/UK_telephone/uk_telephone.html for info on phone wiring.

Robert G8RPI.



________________________________
 From: Chris Wilson <chris at chriswilson.tv>
To: 'Discussion of precise time and frequency measurement' <time-nuts at febo.com> 
Sent: Thursday, 18 July 2013, 18:28
Subject: Re: [time-nuts] Thunderbolt SMPS question
 



> Hi

> It's also likely to have issues if you don't have something between -7 and
> -13 on the V- supply. Current is low (10ma?). A good linear regulator is
> useful on the +12. The +12 rail drops back to < 200 ma under most conditions
> once the oven has warmed up.

> Bob




18/07/2013 18:26

Thanks Bob, Robert and Azelio. I spoke too soon, the damned noise is
back with the TB and divider supplies unplugged. I was really hopeful
I'd cracked it there. Time to call my ISP to get BT out. Living in the
sticks satellite internet is appealing right now :)

-- 
       Best Regards,
                   Chris Wilson.

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