ERICSSON
TELEPHONE No. N2120
 


Magneto Telephones

n2121a.jpg (10396 bytes)
N2120H N2120 Internals

N2120H
Magneto table telephone with one magnet generator


A one-piece table instrument is at all times preferable to one made up of two or more parts, and the magneto type of telephone has been the most difficult to combine in a neat form.

Hitherto telephones for magneto working have been heavy and cumbersome on account of the size of the generators available. With modern magnetic materials a new and highly efficient magneto generator of very small size and weight has been produced. By incorporating this new generator into our already popular moulded case an instrument of excellent symmetry, light and efficient, is provided for magneto working.

The internal apparatus is mounted on a metal base plate which can be completely detached from the case. The apparatus comprises, induction coil, generator, 1000 ohm ringer and gongs, switch springset and cord connecting block, space being also provided for a condenser when required.

The telephone comprises of:-
Micro-telephone N5852, Micro-cord N4021, Inset N7750, Mouthpiece N8634, Receiver N6815, Earpiece N4443, Receiver Diaphragm N4400, Generator handle N55577 and Terminal Block Cord N4324.

The sliding tray fitment is not practicable on this telephone.

Dimensions - 9.25 x 8 x 6
Weight - 7.5lbs

N2120H - Diagram is dated 1939 and 1948.

N2120H - May have also been used by GEC - click here for more information.

N2120K - Specifically made for the Australian Post Office.

These are some of the differences:-

  • 1000 Ohm ringer.
  • A 1.7 uF capacitor in series with the ringer, allowing the use on lines with DC supervision.
  • A 0.4 uF capacitor as part of the sidetone suppression network
  • An additional non inductive 900 Ohm winding on the induction coil as part of the sidetone suppression network, making the induction coil a No. 21A instead of the No. 21 used in the original N2120 versions.
  • The electrical arrangements are significantly different with the intention of improving the sidetone performance compared with earlier circuit designs.  These appear to be a development of the Australian Post Office Research laboratories.

N2120LT has an additional 2uf capacitor which can be brought into use in series with the bell ringer if required (diagram dated 1940).

N2120 is superseded by N2121

Click here for Blueprint of N2120

Click for an article from the Ericsson Bulletin


 

Diagram N57255 issue 3 for Telephone N2120J & S


 

Diagram N57255 for Telephone N2120A3


Additional information on Australian variants

Ericsson No. APO No. Colour Information
N2120H 334MT Black GENERATOR THROUGH DIAL DUMMY
N2120K 334MT   GENERATOR THROUGH DIAL DUMMY
N2120K1 334MT   GENERATOR THROUGH DIAL DUMMY
N2120K3 334MT   GENERATOR THROUGH DIAL DUMMY

APO = Australian Post Office

 
 
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Last revised: June 23, 2020

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