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 11th Jun 2012, 12:12 pm   #1
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default 1920s Direct line telephone/intercom

Hi

I've bought an antique intercom.

My question concerns getting them working!

I have read that all is needed is a multi-core cable and a 9v battery.

Does anyone recognise this set (they look identical/similar to others I've seen on the interwebs) and could advise further?

Thanks!!
Attached Thumbnails
Click image for larger version

Name:	photo 1.JPG
Views:	533
Size:	25.3 KB
ID:	67561   Click image for larger version

Name:	photo 2.jpg
Views:	508
Size:	70.5 KB
ID:	67562  

Last edited by paulsherwin; 11th Jun 2012 at 12:44 pm. Reason: To comply with forum rules
boombox is offline  
Old 11th Jun 2012, 12:51 pm   #2
russell_w_b
Dekatron
 
russell_w_b's Avatar
 
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,684
Default Re: 1920s Direct line telephone/intercom

From memory (I'll check when I get home):

Z = 'Zinc' = negative of your battery.
C = 'Carbon' = positive of your battery.
L = 'Line' = one of your interconnecting lines.
MC may mean 'microphone and carbon', but I'll check on this.
ZE will be 'Zinc and Earth', so you'll need to connect your other interconnecting line here, along with your negative battery connection.

Polarity isn't important, but make them the same both ends. You'll just need a one-pair cable, or even one wire and earth to connect them.
__________________
Regds,

Russell W. B.
G4YLI.

Last edited by russell_w_b; 11th Jun 2012 at 12:54 pm. Reason: Afterthought.
russell_w_b is offline  
Old 11th Jun 2012, 1:30 pm   #3
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
Default Re: 1920s Direct line telephone/intercom

The same terminal labelling is found in the "telephones" section of the GEC catalogue of 1892. Different models use different combinations of the same set of letters, and the MC, ZE, C, and L configuration is only used on a "Hunnings Cone" model, made under licence form the NT Co.Ltd, which has two additional terminals B, B for a "detached bell". The wooden base looks just like that of the "Manchester Microphone" model, but this uses a different configuration of letters, and needed three cells. The "Hunnings Cone" Model was said to require "two agglomerate cells or two dry cells".
emeritus is offline  
Old 11th Jun 2012, 1:32 pm   #4
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: 1920s Direct line telephone/intercom

Thanks, Russell!

So would I need just one battery or two? I presume one. Can I use a standard 9v PP3 battery?

If so, essentially I would need four core bell wire. Two for comms and two for power.

I really hope the bell signalling works. I'm hoping it detects the off hook and signals the other unit on that basis.

Thanks again
boombox is offline  
Old 11th Jun 2012, 1:42 pm   #5
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: 1920s Direct line telephone/intercom

Found some references:-

http://www.richardsradios.co.uk/hunnings.html

http://www.britishtelephones.com/gec/k040.htm
boombox is offline  
Old 11th Jun 2012, 3:18 pm   #6
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: 1920s Direct line telephone/intercom

I would guess that it would have used one or two "Flag" cells (1.5V) in a separate wooden case. The main requirement is to be able to ring the bell, so you need to find the minimum voltage for this by experiment.
A close up of the circuit diagram might help.
AC/HL is online now  
Old 11th Jun 2012, 3:36 pm   #7
richrussell
Heptode
 
richrussell's Avatar
 
Join Date: Jul 2008
Location: Selby, North Yorkshire, UK.
Posts: 979
Default Re: 1920s Direct line telephone/intercom

Ooh - I've got a pair of those. They were in my grandparents house in London when they moved in (1940s). The previous owner was a doctor, and the phone was used for his secretary to let him know a client was waiting. I had them working when I was about 14, but haven't tried since. Mine don't have the labels on the terminals though, which made it more difficult!

I seem to think I had a 1.5V battery at each end, but can't be sure.

Rich.
richrussell is offline  
Old 11th Jun 2012, 6:10 pm   #8
russell_w_b
Dekatron
 
russell_w_b's Avatar
 
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,684
Default Re: 1920s Direct line telephone/intercom

This confirms my earlier post.

Old english telephone connections are:
ZE = Zinc and earth (negative of battery and earth, or return line).
C = Carbon (positive of battery).
MC = Microphone carbon (being the carbon in the microphone).
L = Line.

You'll need a battery in each telephone. Attached is a circuit diagram from Herbert G. White's book 'Telephone Erection and Maintenance' (3/6 net, October 1922). The other end is wired similarly, i.e: L to L; ZE to ZE. Note that the mic is tapped down the battery. 9V may be too much for it, so use three 1.5V cells with a tap off a couple - or simply experiment - the tap may be un-necessary depending on the length of your line.
Attached Thumbnails
Click image for larger version

Name:	tele.jpg
Views:	404
Size:	25.3 KB
ID:	67577  
__________________
Regds,

Russell W. B.
G4YLI.
russell_w_b is offline  
Old 11th Jun 2012, 8:11 pm   #9
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: 1920s Direct line telephone/intercom

Really appreciate this. Thanks all.

I'll try a D cell in each telephone first.
boombox is offline  
Old 11th Jun 2012, 9:33 pm   #10
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
Default Re: 1920s Direct line telephone/intercom

Given that the original design specifies three cells, you may find that a single cell provides insufficient voltage to drive the bells.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline  
Old 12th Jun 2012, 6:52 pm   #11
richrussell
Heptode
 
richrussell's Avatar
 
Join Date: Jul 2008
Location: Selby, North Yorkshire, UK.
Posts: 979
Default Re: 1920s Direct line telephone/intercom

Actually, I'm mistaken - my Sterling U125s only have three terminals. I'm struggling to find a diagram for these - Bob's site is very good, but only really covers 4 terminal phones of this age (though it does list the U125 and it's GEC equivalent).

I think I posted on here about four years ago when I last had a go at getting them going, but nobody knew then. There seem to be plenty of four terminal intercom phones, but not many three terminal ones. Unhelpfully the terminals are just labelled 1, 2, 3.
richrussell is offline  
Old 12th Jun 2012, 8:31 pm   #12
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
Default Re: 1920s Direct line telephone/intercom

Hi Gents, an exactly similar set, with either 3 or 4 wet Leclanche we used on the local railway siding for the winch operated incline down to the docks until the late 50's.

Ed
Ed_Dinning is offline  
Old 12th Jun 2012, 8:45 pm   #13
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: 1920s Direct line telephone/intercom

I dug my one house phone out last night. Externally it is identical to the ones in the photo, but it is much simpler internally. It doesn't have a coil, and the mic and earpiece are simply connected in series.
It has three terminals, L, BL and BT.
Both bell coils are labelled 2 ohms, and over 2 volts is required to ring it, so 2 or 3 flag or Leclanche cells would seem to be the right supply.
According to the label it was manufactured by the Phoenix Telephone & Electric Works.
AC/HL is online now  
Old 12th Jun 2012, 10:01 pm   #14
russell_w_b
Dekatron
 
russell_w_b's Avatar
 
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,684
Default Re: 1920s Direct line telephone/intercom

Quote:
Originally Posted by richrussell View Post
I think I posted on here about four years ago when I last had a go at getting them going, but nobody knew then. There seem to be plenty of four terminal intercom phones, but not many three terminal ones. Unhelpfully the terminals are just labelled 1, 2, 3.
Here's a circuit diagram of a Stirling No:U200. It may be similar to your instrument.
Attached Thumbnails
Click image for larger version

Name:	U200.jpg
Views:	305
Size:	48.3 KB
ID:	67596  
__________________
Regds,

Russell W. B.
G4YLI.
russell_w_b is offline  
Old 13th Jun 2012, 1:07 am   #15
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
Default Re: 1920s Direct line telephone/intercom

Thanks Russell, it's identical, I suppose that was the standard of the day.
1 is L
2 is BL
3 is BT
AC/HL is online now  
Old 13th Jun 2012, 10:47 am   #16
richrussell
Heptode
 
richrussell's Avatar
 
Join Date: Jul 2008
Location: Selby, North Yorkshire, UK.
Posts: 979
Default Re: 1920s Direct line telephone/intercom

Many thanks - that does seem to match up with what's inside the boxes.

I'll give it a go tonight - it also confirms my recollection of having a battery at both ends (though not just a single 1.5V cell).
richrussell is offline  
Old 13th Jun 2012, 11:25 pm   #17
boombox
Pentode
 
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
Default Re: 1920s Direct line telephone/intercom

OK - so the results of my jury rigged setup.

I tried at various times two AND three D cell batteries in each telephone. Battery negative to ZE and battery positive to C.
Line being a connection between both telephones.
ZE was also connected between both telephones.
MC was at times connected directly to battery positive and at times not connected at all.

The push button to ring the bell works - better in one telephone than in the other but I hope that can be resolved mechanically.

I can only VERY faintly hear anything from the earpieces. So faintly I'm not sure it's not just my imagination. There's plenty of voltage so I don't think the problem can be too little power.

Could it be that the mics or earpieces need replacing? Or have I wired it up wrong?

Many thanks.

P.S. Attached a circuit diagram from the telephone's interior.
Attached Thumbnails
Click image for larger version

Name:	circuit2.jpg
Views:	250
Size:	110.9 KB
ID:	67633  
boombox is offline  
Old 14th Jun 2012, 7:41 pm   #18
richrussell
Heptode
 
richrussell's Avatar
 
Join Date: Jul 2008
Location: Selby, North Yorkshire, UK.
Posts: 979
Default Re: 1920s Direct line telephone/intercom

I connected up my three terminal Sterling U125s as shown (A1 to B1, A2 to B2, A2 to batt +ve, batt -ve to A3, and B2 to batt -ve, batt +ve to B3) - and they works a treat

Used two 1.5V AA cells at each end, and the other bell rings when an earpiece is lifted and the button pressed. Sound quality is intelligable, if a bit distorted. But it's loud enough.

It might be worth looking at the carbon microphones on yours if it's very quiet - increasing the voltage isn't necessarily the way to get larger amplitude signals with this type of microphone.

Now to give them a dust and a polish, and mount them on the walls. One in the kitchen and one in the sitting room naturally, so I can ring for tea and biscuits
richrussell is offline  
Old 14th Jun 2012, 7:45 pm   #19
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
Default Re: 1920s Direct line telephone/intercom

Hi Gents, sometimes the carbon granules in the mic capsules get compacted, try gentle shaking or tapping.

Ed
Ed_Dinning is offline  
Old 14th Jun 2012, 9:31 pm   #20
richrussell
Heptode
 
richrussell's Avatar
 
Join Date: Jul 2008
Location: Selby, North Yorkshire, UK.
Posts: 979
Default Re: 1920s Direct line telephone/intercom

Yes - I will probably start a new thread on that subject. Whilst there is nice loud, audible sound, it's very distorted and sometimes goes quiet.

The first thing to do I think is to go over all the contacts and ends of wire and clean them up to ensure it's not just a poor connection or broken wire. But one phone works better when the microphone is vertical compared to horizontal, which makes me think it's not quite right.

But given these two haven't been in proper use for around 80 years, I'm quite happy so far.
richrussell is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 5:45 pm.


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.