UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Telephony and Telecomms

Notices

Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment

Closed Thread
 
Thread Tools
Old 12th May 2017, 7:51 pm   #1
NickG0HIK
Hexode
 
NickG0HIK's Avatar
 
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
Default 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
Attached Thumbnails
Click image for larger version

Name:	Uni.jpg
Views:	259
Size:	63.6 KB
ID:	142484   Click image for larger version

Name:	Ini_2.jpg
Views:	255
Size:	55.2 KB
ID:	142485  
NickG0HIK is offline  
Old 13th May 2017, 1:03 pm   #2
dagskarlsen
Heptode
 
dagskarlsen's Avatar
 
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
Default 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
dagskarlsen is offline  
Old 13th May 2017, 1:08 pm   #3
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default 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?
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 13th May 2017, 3:51 pm   #4
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default 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.
__________________
Kevin
McMurdo is offline  
Old 13th May 2017, 11:05 pm   #5
NickG0HIK
Hexode
 
NickG0HIK's Avatar
 
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
Default 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.
NickG0HIK is offline  
Old 13th May 2017, 11:12 pm   #6
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Info needed on Uniselectors

This may help:-

http://www.samhallas.co.uk/repositor...phones_4_1.pdf
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 14th May 2017, 8:08 am   #7
NickG0HIK
Hexode
 
NickG0HIK's Avatar
 
Join Date: Jul 2010
Location: Ireleth-in-Furness, Cumbria, UK.
Posts: 286
Default 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
NickG0HIK is offline  
Old 6th Jun 2017, 2:56 pm   #8
val33vo
Retired Dormant Member
 
Join Date: Apr 2008
Location: Banffshire, Scotland, UK.
Posts: 191
Default 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
val33vo is offline  
Old 6th Jun 2017, 3:33 pm   #9
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
Default Re: Info needed on Uniselectors

So what piece of equipment is it?
GMB is offline  
Old 7th Jun 2017, 11:51 am   #10
val33vo
Retired Dormant Member
 
Join Date: Apr 2008
Location: Banffshire, Scotland, UK.
Posts: 191
Default 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 )
val33vo is offline  
Old 8th Jun 2017, 10:12 am   #11
M0AFJ, Tim
Hexode
 
M0AFJ, Tim's Avatar
 
Join Date: Mar 2006
Location: Helston, Cornwall, UK.
Posts: 301
Default Re: Info needed on Uniselectors

Brings back memories of oil dag at Monument Exchange as a T2A
M0AFJ, Tim is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 10:35 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.