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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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12th May 2017, 7:51 pm | #1 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Info needed on Uniselectors
Hi,
I'm trying to recreate a piece of WWII aircraft equipment, it uses two uniselectors for the timing, driven from a 25Hz supply. Now I know almost nothing about these devices, but looking on Ebay they seem to be asking quite serious money for these items, but as I have gone so far down this project I jumped in and bought some. When trying them out I could not get my PSU to drive them. Mine measure 100 ohms coil resistance and running them up on the workshop PSU they seem to drive reliably at around 25 volts. I have since found that the ones I need should have a 700 ohm coil. I just presumed all uniselectors where made equal and designed to run from telephone supplies around 48v ?, but it appears not. I wonder what is the most common type and if anyone can I.D. the one in the attached copied photo as this is the type I require, also attached is a picture of what I bought. I don't want to end up wasting more money |
13th May 2017, 1:03 pm | #2 |
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
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Re: Info needed on Uniselectors
Aircraft equipment is far out of my knowledge, but telephone exchanges used to use 70-100V ringing current at 25Hz. (most of Europe) Germany and some countries did use 60V. I have a transformer in front of me here marked Prim: 15V 25Hz Sek:88.6V 50mA
If that one my help you, you may get it for the postage from Norway The parcel costs NOK 302 A letter will cost NOK 91 https://www.posten.no/sende/pakke/ut...gVYRoC2Qjw_wcB dsk |
13th May 2017, 1:08 pm | #3 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
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Re: Info needed on Uniselectors
Telephone exchange uniselectors certainly ran off 50V DC. What I can't remember is whether there was a resistor in series with the coil.
Could you not rewind the coils with more turns of thinner wire to give approx 700 ohms?
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
13th May 2017, 3:51 pm | #4 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
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Re: Info needed on Uniselectors
They were also used in industrial equipment, I'm sure I played with some as a young teen when I wouldn't have had 50V to run them off, but I got them to work somehow.
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Kevin |
13th May 2017, 11:05 pm | #5 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Info needed on Uniselectors
Thanks for the info,s.
I have certainly considered rewinding to 700 ohms, I've removed the outer insulation to expose the windings and there is a lot of very fine wire, so it's not a job that I would take on lightly. I may put this project on the back burner for a while, till I can get a bit more information. I remember seeing at the museum of internal fire a good exchange system setup and looked like chaps who knew what they were doing. So another visit maybe in order. |
13th May 2017, 11:12 pm | #6 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
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Re: Info needed on Uniselectors
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
14th May 2017, 8:08 am | #7 |
Hexode
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
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Re: Info needed on Uniselectors
Thanks,
That was just the sort of information I was after, but did not find that document. So 100 ohm coil is for 50v and it mentions that four other voltages are available. Armed with that, it will help the search Nick |
6th Jun 2017, 2:56 pm | #8 |
Retired Dormant Member
Join Date: Apr 2008
Location: Banffshire, Scotland, UK.
Posts: 191
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Re: Info needed on Uniselectors
I used to work as a technical officer in a largish strowger exchange and all the unis ran from 50V even the (MUGS ) motorised uni group selector, however the MUGS had electric motors rather than being driven with a magnet and pawl system like the one in your attached image
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6th Jun 2017, 3:33 pm | #9 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Info needed on Uniselectors
So what piece of equipment is it?
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7th Jun 2017, 11:51 am | #10 |
Retired Dormant Member
Join Date: Apr 2008
Location: Banffshire, Scotland, UK.
Posts: 191
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Re: Info needed on Uniselectors
judging from image 2 it is a standard telephone exchange type uniselector that has been removed from the circular contact bank, it will most likely have 25 steps to complete a half circle which will cover the 25 contacts, its hard to judge from the photo but it may have staggered wipers meaning it would have 50 possible outlets which would mean it would take a whole circle to search every possible outlet contact, normal telephone exchange types for customer access would have the wipers inline so would only cover 25 outlet contacts but be able to hunt twice as fast, the only staggered outlet type were used on test equipment where speed of search was not a prime factor
MUGS were not used for customer access but were very fast in action and could search a large number of contacts very quickly maybe a hundered ( its so long ago I cant remember exactly ) they were frightening to watch in operation as they spun so fast and when they found a free contact a pawl was energised which cut the drive to the motor and locked the drive in a few milliseconds, MUGS were used in the trunk exchange where it was necessary to search a large number of junctions very quickly, in the exchange I worked in they were only used as part of the international network and in our case as far as I remember it was London junctions to the London Mondial exchange ( Mondial house ) |
8th Jun 2017, 10:12 am | #11 |
Hexode
Join Date: Mar 2006
Location: Helston, Cornwall, UK.
Posts: 301
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Re: Info needed on Uniselectors
Brings back memories of oil dag at Monument Exchange as a T2A
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