Siemens Brothers Neophone 310, 311, 312 and 366

Novice collectors are often baffled by these 200-type telephones with 300-series numbers on the paster diagrams but that’s because Siemens Brothers (SB) had their own numbering system. The company named all of them Neophones, although the British Post Office (BPO) favoured the circuitry and shape of these instruments, only one pattern, the type 310, was adopted by the BPO. According to Siemens’ advertisements at the time  this was ‘the world’s most efficient telephone’, ‘Not only exceptionally handsome in appearance and convenient to use but definitely superior to any other telephone as regards speech transmission efficiency and articulation’.

Type 310 is in effect a BPO Telephone No. 232 permanently fixed to a Bellset 26.  Type 312 is a one-piece instrument with a larger case and built-in ringer; the mouldings are also much ‘sharper’ than the rounded edges of the 310.  Click here for more information on the 312.

The 311 was the matching wall instrument, compact and attractive but not adopted officially by the BPO (it was very popular on the Southern Railway and in Canada, however).  The case design (but not the circuitry) was also used by ATE (model T4127) and during World War II a number of these phones were bought by the BPO for providing emergency telephone service to bomb-damaged buildings (the phones were small enough to fit inside a locked wall box).  It is unclear whether the BPO bought SB or ATE telephones.  Its ringer had the standard 1000-ohm impedance whereas the export model 366 (made for Saskatchewan’s telephone system in Canada) had 2000 ohms.  Siemens wall telephones nos. 83 and 85 were similar but had older transmission circuitry.

Two patterns of handset were fitted to the phones, one identical to the BPO Telephone No. 164 design and another with a slotted cover instead of the normal ‘spit cup’ over the microphone.  This slotted cover occasionally turned up on BPO telephones, as Mouthpiece No. 18.

The telephone was supplied with a dial for automatic exchange systems of a dummy dial black for C.B. systems.

The pattern of bellset used on the 310 is different from that  adopted by the British Post Office (Bellset 26); it is considerably smaller and half an inch shorter in height than the standard Bellset 26.  It has a semi-circular terminal strip, a fairly standard bell mechanism and slightly smaller gongs (two and a quarter inches in diameter instead of two and a half inches).  There is a No. 16A induction coil with wooden coil cheeks and the base plate is universal as it can be used for the table bellset and the wall phone bellset, having two holes to line up with a wall bracket.  The table set has a light gauge pressed metal cover over the base plate, with  two large openings for vents which have a mesh cover.  On this plate is quite a large transfer with Siemens Brothers & Co. Ltd. London and the relevant British and Commonwealth Patent numbers.  The Bakelite case of the bellset is also universal and does not have a cover as the standard bellset does; this open top enabled them to mount the equivalent of a GPO Telephone No. 162 directly above without external cordage between telephone and bellset.

Colours:
Black, Green and possibly others.

Users:
These telephones saw widespread use on private systems installed by  Siemens Brothers Private Telephone Department, in a number of countries abroad (particularly Saskatchewan in Canada, the Bombay Telephone Company in India plus  administrations in Australia, New Zealand, Egypt, Southern Rhodesia and the Union of South Africa) and on the former Southern Railway and British Railways Southern Region.  A number have been re-imported from Canada for sale on the UK collector market.

Further information:
Engineering Supplement to the Siemens Magazine, October 1931; Siemens Brothers Neophone Type 300, pamphlet no. 509A, July 1932, held in the BT Museum, London.

Circuit Diagram

Conversion to UK Plug and Socket

When removing the case - undo the two screws and pull them towards you as far as they will go.  The case then opens on the hinge and the screws do not foul any components or wiring.

1. Remove the white wire from the capacitor.

2. Connect the Red wire of the line cord to terminal L2.

3. Connect the White wire of the line cord to terminal L1.

4. Connect the Blue wire of the line cord to terminal C.

5. Insulate the Green wire of the line cord as it is not used.

6. Connect a 3.3k resistor between E and L1 terminals.

7. Connect a Rectifier Element No. 205 to the red and green wires of the handset cord.

Wiring in directly
If you do not want to use a telephone line cord, but wish to wire the telephone directly into house wiring using telephone cable (6 wire) then follow these instructions:

1. Wire L1 to socket connector 5 using Orange/White of the cable.
2. Wire L2 to socket connector 2 using Blue/White of the cable.
3. Wire C to socket point 3 using White/Blue of the cable.

More Pictures of the 311

Click here for a spare parts picture
 

Last revised: March 25, 2022

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