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Old 11th Apr 2020, 8:46 pm   #1
Oldcodger
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Default N diagram /circuit diag anyone

Found this socket in amongst my old sockets . From what I remember it's fitted to older BT systems to ring an extension bell from extension phones and needs a 50v supply of correct polarity ( something which a lot of customers did not realise , resulting in one of the power resistors -R5/R6 ?, going up in smoke).
All I can find on the socket is a number DPA1448A which means little to me as I never got involved in BT systems.
Anyone from BT systems remember this one and point me to an N diag or circuit diagram please.
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Old 11th Apr 2020, 10:05 pm   #2
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Default Re: N diagram /circuit diag anyone

Quote:
Originally Posted by Oldcodger View Post
Found this socket in amongst my old sockets . From what I remember it's fitted to older BT systems to ring an extension bell from extension phones and needs a 50v supply of correct polarity ( something which a lot of customers did not realise , resulting in one of the power resistors -R5/R6 ?, going up in smoke).
All I can find on the socket is a number DPA1448A which means little to me as I never got involved in BT systems.
Anyone from BT systems remember this one and point me to an N diag or circuit diagram please.
Is it marked 'BT' on the front?. I've worked with all sorts of BT and other phone systems since I first saw a Line Jack in 1980 before they had been introduced to the public network. I've never seen one like that one before. It isn't shown in any N diagram - I've got 80 plus volumes which cover 1917 to the last issues and all that BT show for extension bells not rung from the AC line current, is a 'plug-in adapter that split the 'bell wire' on No 3 on the LJU to operate a relay with a REN greater than 4. The fact that the Krone connector is marked A/B/C & D rather than 1- 6 tends to indicate it is not for use with a standard 2 wire telephone circuit. I have a similar sized PCB with a BT 6 way LJU type socket in the middle with lots of components on it and a tiny what looks like a buzzer. Never been able to find where/what it was used for.
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Old 11th Apr 2020, 10:21 pm   #3
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Default Re: N diagram /circuit diag anyone

It's got the old style BT logo on the front The short line with a longer line at right angles ,with a set of two dots to the right.And all in a circle.
From memory ,I seem to remember this type of socket fitted to possibly a Herald extension, to let an extension bell ring from a system extension.
Looking at the socket, it seems so similar to a "ringing generator 2A" , which was operatd on a mains supply.

Last edited by Oldcodger; 11th Apr 2020 at 10:36 pm.
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Old 12th Apr 2020, 8:02 am   #4
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Default Re: N diagram /circuit diag anyone

You mean this one:
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Old 12th Apr 2020, 8:05 am   #5
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Default Re: N diagram /circuit diag anyone

By the way, I misremembered it as having three dots, which would have made the upper bar a "B" in Morse code.
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Old 12th Apr 2020, 1:51 pm   #6
Graham G3ZVT
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Default Re: N diagram /circuit diag anyone

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Originally Posted by Dave Moll View Post
By the way, I misremembered it as having three dots, which would have made the upper bar a "B" in Morse code.
A missed opportunity, I always thought.

The current logo is so unimaginative, but no doubt someone got richer by designing it.
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Old 12th Apr 2020, 3:25 pm   #7
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Default Re: N diagram /circuit diag anyone

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Originally Posted by Dave Moll View Post
You mean this one:
That's the one ,Dave.
Thinking back, this socket was fitted to one port on something like a Herald ( possible Pentara) with a four wire termination on it ,along with 50v from the switch and a bell out pair.
I've never fitted one as I spent most of my time replacing BT systems with Panasonic systems ( except when the firm did either TIG or MIG welding when I sent the order back for a technical inspection as Panasonic did not like MIG/TIG).
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Old 12th Apr 2020, 5:35 pm   #8
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Default Re: N diagram /circuit diag anyone

I notice that you mentioned the socket last October in the context of ringer boosting (post no. 7). Found while googling the number at the top.
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Old 12th Apr 2020, 9:18 pm   #9
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Default Re: N diagram /circuit diag anyone

Dave- I mentioned both variants as solutions to ringing, with no clue to what they were/what they did or circuits.
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Old 13th Apr 2020, 6:41 pm   #10
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Default Re: N diagram /circuit diag anyone

Hi, I once owned one of these sockets which came with an Ambassador 2+4 system.
From memory the socket allows an additional bell to be associated with the system phone connected to it. I think there's a link in the system phone which has to be opened to allow the external bell to operate.

I can see no reason why the socket wouldn't also operate on the the Senator 5 + 10 and possibly other systems of a similar design which use dedicated system phones.

Regards

Andrew
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Old 13th Apr 2020, 7:17 pm   #11
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Default Re: N diagram /circuit diag anyone

If it works with the Ambassador, I would expect it also to work with the Senator, given that, as far as I know, the only real functional difference between them is how exchange lines are accessed.
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Old 14th Apr 2020, 4:37 pm   #12
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Default Re: N diagram /circuit diag anyone

Quote:
Originally Posted by Dave Moll View Post
I notice that you mentioned the socket last October in the context of ringer boosting (post no. 7). Found while googling the number at the top.
I did as a possible help to a problem as some folk might not know these bits existed.
But back OT- anyone got a circuit diagram for one of these ?
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