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Old 24th Mar 2007, 9:57 pm   #1
DoctorWho
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Default GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I've been restoring a 2+4 GPO dolls eye switchboard which is now working very well.

I was just wondering what voltage and current rating the power supply is supposed to be for these?

I'm currently using a 12V DC supply, but is this correct? I know they use a lower voltage than the floor standing corded boards, but I've never been able to find the exact specification of the original power supply for one of these boards.

If anyone can clarify for me the correct voltage and current rating of the original batteries/power supply I would be very grateful.

Many thanks,

Peter.
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Old 24th Mar 2007, 10:36 pm   #2
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Peter,

12V is about right.

The 2+4 is unusual. I have the 1+3, and there was a larger common size (4+8?). The supply can vary, and limiting resistors can be fitted if an existing supply of higher voltage is already on site.

Jim.
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Old 24th Mar 2007, 10:43 pm   #3
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Thanks Jim, I was guessing really with the 12V, so I'm grateful to know it's about right.

The switchboard works amazingly well, it's in nice untouched condition, it looks like it last had a "check-up" by the GPO in 1958, interestingly the fuse wire was not intact, but I just simply soldered in a new piece and everything worked correctly, I can't see anything wrong which would have caused an overload.

These little tabletop switchboard are very attractive little units, I wonder if any are left in service anywhere (as originally installed).

Out of interest what voltage would you use for the 1+3 and also the larger 4+8 (possibly 3+9)?

Peter.
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Old 25th Mar 2007, 1:03 am   #4
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Hi Peter,

I think 12V was the "standard" supply, with only the current requirements changing, although they only draw current when the phones are off hook (energising current for the microphone, and current for the dolls eye indicator / relays). They were carefully designed to minimise current use.

Jim.
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Old 25th Mar 2007, 10:50 pm   #5
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Thanks Jim, in that case it was a good guess. I know the floor standing corded models ran on something like 48V, but obviously a small tabletop exchange wouldn't need that kind of supply.

They were well designed and engineered units, which I guess is why so many have survived so well. I just cannot imagine anything being made of such solid and high quality wood to-day for rental purposes.

Peter.
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Old 29th Mar 2007, 12:12 pm   #6
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

How about a picture, Peter?
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Old 29th Mar 2007, 3:16 pm   #7
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Good point Nick, here you go, all up and running now:
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Old 29th Mar 2007, 3:22 pm   #8
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Very nice
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Old 29th Mar 2007, 5:10 pm   #9
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Thank you.
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Old 29th Mar 2007, 10:40 pm   #10
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I have to agree to about the switchboard being very nice and notice that you have a Trimphone connected to it.
Out of interest does the Trimphone "ring" ok from the switchboards built in magneto generator? Most Trimphones have trouble ringing on modern day exchange lines (as I have probably mentioned elsewhere in this forum)

Regards
Andrew
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Old 29th Mar 2007, 10:49 pm   #11
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Hello Andrew,

Thanks for your kind words. yes indeed, the Trimphone does ring perfectly well with the switchboard. I have a few Trimphones in my collection and I convert them in exactly the same way as the 706's, by removing the links for the internal ringing condenser and using the blue lead to connect the ringer to the ringing condenser in the master socket.

All of mine ring without any problem on our line, we have a lot of telephones connected to the line, but not all have their bells activated of course.

If you have a problem with your Trimphone/s ringing why not start a thread about that, maybe we can compare notes? I've certainly found at least two completely different Trimphone warbler circuit assemblies.

All the best,

Peter.
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Old 29th Mar 2007, 10:52 pm   #12
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I have a swichboard larger than that bck in my mums shead , Ive no idea wat type , not seen it properly in 16 years its about time it found a new home , I Have no space. going free to anyone near chippenham ! just let me know .

there used to be a working example like peters in chippenham museum , i used to love looking at it .
My mum worked as a telephonest in chippenham from the late 40s till 1967 she was familier with all the exchange types from the manual onwards , and while she was pregnant with me was employed to run DEVIZES switchboard while it was being modernised
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Old 30th Mar 2007, 3:18 pm   #13
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I'd love it Paul, any chance of being able to post it (ay my expense of course)?

I bet your mum had an interesting time on the exchanges, it's a shame that personal touch is long gone now, very sad.
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Old 30th Mar 2007, 9:05 pm   #14
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

ithink its at least 3 foot long , condition i dont know, in memory i think the varnish was poor .I need to look at it first , though I expect its very heavy, not keen on posting it .
mum has plenty of stories about the early days . Supervisors were very strict , listening in to royalty etc
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Old 30th Mar 2007, 10:42 pm   #15
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Understood Paul, if it is viable I could always have a courier collect it from you, let me know what you think.

Thanks again.

Peter.
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Old 28th May 2007, 4:23 pm   #16
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I have powered my 2+4 from a PP9 battery in the past when i was desperate! It now runs very well off of a 9V DC supply via a plug top power supply
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Old 27th Oct 2007, 8:49 pm   #17
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Wink Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

This is interesting chat to me because I have a 10plus30 standing switchboard which is great nostalgia as my wife was the telephonist/receptionist when we were in our teens back in the late fifties. I power my switchboard also with 9volts dc and it works pretty well with extension phones (2) but I can only ring them with the emergency generator. I would love to be able to use the ringer switch and make it more authentic for normal use.I have been told that a ringing converter is needed. Can anyone give me information on this aspect?
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Old 27th Oct 2007, 11:12 pm   #18
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

I also have a floor standing 5+25 plug and cord switchbpard of the type you describe, and they are very easy to get back operational.

I bought an original GPO power supply from Telephone Lines in Cheltenham and connected that up, it provides the power for the switchboard and also the ringing current for the ringing keys, you can then simply flick a switch to use the hand generator if necessary.

It's well worth restoring these dolls eye switchboards back to full working order, they are so well made and so reliable.
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Old 28th Oct 2007, 10:01 pm   #19
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Thanks a lot for the information about the power supply. Will I connect it to the same point that I connect the 12volt dc? Excuse my ignorance but I am a poor mans GPO engineer and I have to be very carefull because my young grandchildren love to play switchboard operator like their grandma. I will contact Telephone Lines Cheltenham as you suggest. Thanks again....Alec
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Old 29th Oct 2007, 11:29 am   #20
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Default Re: GPO 2 + 4 Tabletop Dolls Eye Switchboard Power Supply.

Yes indeed, there will also be 2 terminals to connect the rining current supply to, just take care there if young children are using the switchboard as you can get quite a jolt if holding a plug in your hand whilst holding down a ringing key.

Telephone Lines are very helpful.
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