Can anyone identify and date this Ericcson Telephone please?

[DoctorWho]

I recently bought this rather nice Ericsson telephone, it's in pretty good chape, the handset is complete, there was never supposed to be a horn, there are 2 slits which allow the microphone to pick up the speech. On the base is the number 2270A. There is a circuit diagram inside the base, but no model number. It is a Local Battery model. Turning the magneto handle makes the bells ring, and the original 60core cable is present which, presumably, went to a wooden terminal block. It's connected up and working well.

If anyone can identify the model and tell me what age it is I would be very grateful. Also, there are two hinges on the side of the main body of the telephone, but no obvious way to open it up. I don't need to open it as it's working fine, I'd just be curious to know how it opens.

Thanks for any information.

Peter.

[russell_w_b]

Originally Posted by DoctorWho

If anyone can identify the model and tell me what age it is I would be very grateful. Also, there are two hinges on the side of the main body of the telephone, but no obvious way to open it up. I don't need to open it as it's working fine, I'd just be curious to know how it opens.

Thanks for any information.

Peter,

It looks remarkably like the Ericsson Table Instrument made at Beeston, Notts, pattern '1907-All Steel', with a slight variation of the handset cradle. I can post a pic of an advert, if you wish.

So, I would guess, 1907.

Are there any screws holding down the top-plate (upon which the cradle is mounted)? If so, removal of these and removal of the magneto handle will likely allow lifting-off of the filigree box, revealing a four-horseshoe magnet magneto. The advert to which I refer states that: 'The whole of the working parts are mounted on the base. The top and cover are removable'.

[jim_beacon]

It is a "corporation set", and they were in production for quite a long time, and in various versions (CB, LB etc.), also known as the JYDSK telephone. They were introduced in about 1904, and lasted well into the 20's.

Mine is currently on loan to a Bath guesthouse, where it is in period.

Jim.

[DoctorWho]

Russell - Thanks for the information, yes please I'd appreciate seeing the advert.

There are no screws holding down the top plate, and yet there is a hinge on one side, so it obviously opens up some how, I have no idea how though. It's the same at the bottom, another hinge, but no obvious way as to how to open it. I imagine that the horse shoe magneto assembly and induction coil are inside that casing?

Jim - Thanks also for this information. Out of interest, why were they known as "Corporation Sets" and what does "JYDSK" stand for? Interesting that they were around for a few years, I wonder when the last went out of service? This one is LB, but workd perfectly well on a CB exchange. Sounds like yours loos ideal in the Bath gues house, is it connected up?

Peter.

[russell_w_b]

Originally Posted by DoctorWho

Russell - Thanks for the information, yes please I'd appreciate seeing the advert.

Peter.

Peter,

Advertisement attached. I asked about the screws because I have a later version of this instrument - model number N2115T - which is equipped with a bakelite type 164 handset, and a not-so-elegant bakelite cradle similar to that of a type 232 instrument. It has a couple of large screws either side of the cradle-set base.

[DoctorWho]

Thanks Russell, that's extremely interesting to see, thanks for posting it here.

All the best,

Peter.

[jim_beacon]

Peter,

no, mine isn't connected up (the guesthouse has a Siemens digital exchange - I suspect it is allergic to magneto 'phones!).

Corporation comes form the extensive use by local authority telephone services (pre-GPO takeover), and I think that JYDSK refers to the Danish telephone service of the time, who may have been the original customer.

Jim.

[DoctorWho]

Thanks for explaining Jim, that certainly makes sense. I suppose their were local telephone companies just as there were local electricity supply companies and the like. Interesting about the Danish telephone service being JYDSK.

As for your telephone, you never know, a good crank of the magneto may well do the digital exchange the power of good. Time for them to perhaps install a manual switchboaard??

Peter.

[dagskarlsen]

Originally Posted by DoctorWho

Russell - Thanks for the information, yes please I'd appreciate seeing the advert.

There are no screws holding down the top plate, and yet there is a hinge on one side, so it obviously opens up some how, I have no idea how though. It's the same at the bottom, another hinge, but no obvious way as to how to open it. I imagine that the horse shoe magneto assembly and induction coil are inside that casing?

Jim - Thanks also for this information. Out of interest, why were they known as "Corporation Sets" and what does "JYDSK" stand for? Interesting that they were around for a few years, I wonder when the last went out of service? This one is LB, but workd perfectly well on a CB exchange. Sounds like yours loos ideal in the Bath gues house, is it connected up?

Peter.

I do not remember, but try to look for a hole to put in a little needle to release a spring lock on the opposite side of the hinges. (You may have to remove the crank first)
dsk

[chipp1968]

I believe variations of this type of phone and the skeleton type were available from the late 19th century into the 1930s ,and apparently some remained in use on the railways untill the 60s if not later

[russell_w_b]

My version (model number N2115T) was used to communicate between the aerial tuning-houses and the main building at BBC Washford MF transmitter, so must have been installed in the 1930's.

[beery]

Hi Peter,
try this...
The magneto has a change over switch at the back which operates when you start to turn the handle. Use a bit of sleeving to insulate the magneto end of the switch so that the magneto will not be switched into service.
conect a 3V battery (two 'D' cells in series) to the battery terminals and connect L1 and L2 across the line. It should work for incoming calls, but it would be best to insert a 3K3 resistor in series with the bell coils.

Well I say it should work. It all depends on whether the bell coils are connected via a capacitor. You may find that they are simply connected straight across the line in which case the bell hammer will stick to one side (that is stick as opposed to flick). If this happens then you won't be able to use it straight off, it all depends on the type of circuit employed.

Worth a try though and it can't really do any harm.

Cheers
Andy

[dagskarlsen]

Peter can you please take a photo/scan of the wiring diagram, and post it.

My guess is that its no cap in series with the ringer. The magnetos from Ericsson has often had a centrifugal switch, this may easily be manupulated if you want to do so.
A solution as Andy sugested will also result in dc current thru the receiver, the line polarity may affect on the quality of the received signal, but uses to work well. This solution was used by some telco's in the first periode of using C.B.
dsk

[DoctorWho]

Thanks for your replies, you're right, the telephone has no ringing condenser at all. When I get the chance I'll take the base off and, if there is a circuit diagram, I'll scan it in an dpost it here.

All the best,

Peter.