SIEMENS BROTHERS
CENTENARY NEOPHONE

THE CENTENARY NEOPHONE

Designed by John Barnes of Allen-Bowden and put into production in 1958, this phone was the modern version of the world famous Neophone. It celebrated the launch of the Siemens Brothers Company in 1858 and had an artistically designed case and handset moulded in impact resisting polystyrene. Due the the shape of the case, surrounding the dial, it was nicknamed "The Horseshoe Phone". This area was intended to be used to display letters for countries that needed lettered dials, but was usually left blank.

The handset on the original version was moulded in two parts and the line along the of the handset was meant to hide any excess adhesive. The handset weighed 7oz (200gms). On later versions the handset was moulded in one piece. The handset cord was a 3 way fabric type.

The case was available in Black, Ivory and Pale Grey. Handset in Black, Ivory, Dark Grey, Red, Green, Maroon and Oatmeal. The case was held in place by two self tapping screws.

The standard telephone consisted of a high performance transmitter and receiver, with closed circuit induction coil, 2500 ohm ringer with adjustable bias spring and a Standard British Post Office dial, with external letter ring (printed on the casing around the dial) as illustrated an optional extra. It was tropically finished, dust and insect proof. Probably one of the first phones to have a printed circuit board.

Hull Corporation customer

Extra-light handset weighing only 7ozs (200 gm).
Complete with black line cord, 2-way or 3-way as required, 4' 6" (l37mm) long and 3-way terminal block.

Height: 5.25" (133 mm)
Width: 9.5" (241 mm)
Depth: 8.25" (210 mm)
Weight: 3.4 lbs (1.53 kgs)

600 Models
Called the Telephone 600, the original circuit board for the standard line model had provision for 9 terminals although in practice terminals 1, 3 and 6 are missing and there is a hole in the circuit board where each terminal should be. Even though these terminals are missing, the rest of the terminals are numbered as if the missing terminals are still there.

The base had holes punched out to allow the sound of the bells to be heard. These holes were covered by a thin layer of plastic which is assumed to stop insects entering the telephone.

The bell gongs are inverted and the bell ring has a cranked swinging arm. There is also a wire adjuster on the bell ringer probably acting as a bias spring.

Only four wires connected the dial and terminals 2 & 3 on the dial were linked together.

The dial was connected as follows:-
1 - Slate (Grey)
2 - Brown
4 - Pink
5 - Orange

Model No. 602A/A
Telephone with a push button, providing for operator recall or executive right of way facility etc.

Model No. 603
A special version of the No. 602 readily adaptable for use over short lines.

9XX Models
Model No's 904, 906 and 908 were table models, whilst No's 980 and 981 were wall mounted telephones. They all used the 11 terminal circuit board.

A transistorised regulator could be fitted to the No. 904 model (see picture below for connection) and this was achieved by replacement of the 470ohm resistor by the regulator. A Regulator Type 3 and is fitted to the telephone by means of the rear fixing screw for the circuit board. The attenuator leads also must be placed in the parked position.

For short line working an attenuator could be activated. This is achieved by the two pin plugs with pink wires which would be unplugged and moved to the two two drilled holes adjacent. The telephone would then be attenuated for short line working.

The bell gongs are not inverted and the bell ringer has been changed so the clanger is underneath with no crank.

The bell adjustment is still in place but there are no holes punched in the base.

The dial is a Dial, Switch No. 38 which is a figures only dial with a white background and stainless steel fingerplate. Dial connection is the same as the early models.

The No. 906 model was fitted with a transistorised automatic regulator and a press button in the top of the case. The regulator was fixed by the Terminal 4 screw. This phone could be used on party lines and have a dial lock fitted.

The No. 908 model could also be used on Shared Service lines. This necessitated the installation of a special terminal plate fitted to the telephone by means of the rear fixing screw for the circuit board. This terminal plate was populated with three terminals, a Capacitor and a Thermistor.

Model No. 904
Short and long working affected by an attenuator (see picture below).
1000 bell ringer.
Receiver No. 62A fitted.

Model No. 906
Fitted with a press button and an automatic regulator.
2500ohm ringer.

Model No. 908
Normal line working with fixed transmission.
2700ohm bell ringer.
Resistors 1000ohm and 220ohm omitted.
Resistor 150ohm is replaced by a 100ohm resistor.
Resistor 470ohm is replaced by a wire link.
Receiver No. 100219 fitted.

Additional Information
One of the first British designed plastic telephones the Centenary Neophone was a reasonable design with an unusual case and a strange looking handset. The case was made from Polystyrene and the phone was fitted with a circuit board that had all components fitted to it and it was adaptable to shared service. The handset was a let down as it was really too light in weight. It still used the standard transmitter and dial but the receiver was changed to the latest rocking armature type.

The cases have also discoloured over time with the grey and ivory being affected the most.

AEI took over Siemens Brothers and later Centenary Neophones can be found with AEI printed on the rear of the case.

On many Centenary phones the circuit diagram can be found folded up and slipped under the circuit board.

The phone uses a Transmitter, Inset No. 13, which will probably not be working that well. It is possible to replace this a Transmitter, Inset No. 21 (with the grey centre). Discard the transmitter casing and fit the insert and lid in place of the No. 13.

Many of these were sold to the Hull Corporation. It appears that AEI needed to off load their stock as the more superior Telephone No. 706 was being introduced. The No. 706 had a better receiver and a short/long line regulator. Whilst penetration was small into the UK the phone was exported abroad especially to South Africa and other Commonwealth countries.

Click here for the AEI variant

Click here for circuit diagrams of all variants

Click here for conversion to new plug and socket


Automatic variant	Central Battery (CB) variant

Internal view of the early model 600 model

600 Model - Standard line telephone
Note inverted bell gongs and missing components

600 model - Standard line telephone


600 model with cracked gong arm Inverted bell gongs and cranked bell clapper arm Bell adjuster is the wire to the left of the clapper arm	904 model with inverted bell ringer Bell gongs are now not inverted Bell adjuster still in place

Internal view of a 904 Model

904 model - rear view

904 model - front view

904 model
Close up of the attenuator connectors. These two pin plugs would be unplugged and parked in the two
hole shown behind them. The telephone would then be attenuated for short line working.