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Custodian for the future.

PostPosted: Sat Feb 16, 2019 9:34 am
by Scaleyback
It's not mine you see.. Well technically I own it, but it's more than that. I just maintain the system, until it is time to hand over to the next person. Not only is it one of my life's works and passions, but it lives and moves and also enthralls those who see it.
Today, the same job can be done with and aerial and an Arduino board, but there is no interest, no 'life' in that, nothing to get excited about or wonder at.

It is a long story which i won't go into now, but during my time working at the PO (later BT), I ended up looking after the exchange clock system. When the Strowger exchanges got decommissioned in the 1990's, most went for scrap, but I went around acquiring what I could and after some years I was finally able to build up a representative system, which includes automatic daily synchronisation.


The sounds change, a clock will go in and then out of sync with one of the others. The sound of the relays alter for the same reasons. That 6 second one, lower right relay unit is a little loud... Should I go check the spring tensions?

Yes, you can do it everything here with an Arduino or two, but show me the passion in that...

(Ok, bit of a dramatic introduction, but I got halfway through typing, "Hello, I am Simon and I have a GPO clock system..." When I thought, "Oh, to hell with that!"). So hi to everybody and it is so nice to see this stuff preserved and hopefully working.

Re: Custodian for the future.

PostPosted: Sun Feb 17, 2019 11:01 am
by Lucien Nunes
Hello and welcome. That looks like an effective and reliable way to tell the time! Do tell about the method of synchronisation...

Re: Custodian for the future.

PostPosted: Mon Feb 18, 2019 12:21 pm
by Scaleyback
Originally, the clocks received a pulse relayed from the Royal Observatory at greenwich, over the telegraph network which forcibly corrected the positions of the 30 second count wheels once a day, typically at 10am. The clock system would then correct any 1 second clock at the top of the next hour.

The telegraph time network closed a long time ago, but I have an MSF receiver and pulser card, one output of which sends a 1 second daily pulse to operate the synchronisers in the master clocks, with the system then correcting the ! second clocks one hour later.

Re: Custodian for the future.

PostPosted: Wed Feb 27, 2019 11:17 am
by Kevin Wood
Fascinating. Makes my home made nixie clock look decidedly lacking in commitment!

Re: Custodian for the future.

PostPosted: Sat Apr 13, 2019 7:22 pm
by kelyselectric
Wow thats an impressive clock system well done for preserving it. I totally agree modern computerised systems have no soul and I cant imagine that any one will get excited about present g them when they get replaced. I think older kit has personality something modern gear lacks. Just a final question does all that gear run from 55 volts DC like most exchange gear does?