GEC Sonic 70 overview
The Sonic 70, launched in April 1966, was
yet another attempt to simplify the design of the Telephone
the same time modernising the shape of the telephone a little and
adding the contrast of an aluminium front lip. A single-coil
ringer was fitted, with an optional loudness control, and the
cradle plungers were made of Delrin plastic. A hand hold was
provided at the rear of the instrument to make it easier to
Two-tone green, two-tone grey, black and white.
None known. The
product appears to have been a failure.
See also TEL 42T/ATT
The Sonic 70 has been designed specifically for the
Administration that requires a simple efficient telephone. Market research has
shown that current telephones embody many facilities which are seldom used; this
fact has greatly influenced the designers of the Sonic 70 and the result is an
efficient single-subscriber instrument at low cost.
The basic high-quality performance and reliability that
have made G.E.C. telephones acceptable to Administrations throughout the world,
are retained. The transmitter, receiver and dial are the same components
that have proved themselves in many millions of telephones already in service.
The case is moulded in scratch-resistant plastic that withstands rigorous
use in climatic extremes. Special attention has been given to ensure that when
the handset is replaced, it will
always 'walk' into the correct rest position. A hand hold is moulded into the
rear of the case to facilitate carrying the complete instrument. The simple
contemporary lines of the new design minimize dust collection.
The handset, moulded in the same material as the case, is light in weight
and combines a high degree of user comfort with maximum transmitter efficiency.
Its shape ensures that, with the receiver held to the ear normally, the
transmitter is located in the most efficient position.
The carbon-granule transmitter and the rocking-armature receiver provide
clear speech reproduction with low distortion over a wide speech-frequency
For the convenience of the user, alternative lead-out
points for the handset cord are Handset cord location located at either side of
the telephone base.
Either the G.E.C. articulated-trigger dial or the new G.E.C. moulded-plastic
dial is available for use in this telephone and is recessed into the case. The
dial is connected to the base terminations by a cable form long enough to
The finger plate is made of transparent plastic, so that
the figures can be viewed through it and are always visible; thus, the risk of
dialling error is minimized. A wide range of number rings is available to suit
the requirements of individual Administrations.
The cradle switch springset is operated by "Delrin" plungers. It is
assembled on the case and connected to the other components by the same cable
form that connects the dial.
The single-coil ringer has a pleasant purposeful sound and will operate from
all normal exchange ringing supplies. A bell volume control can be fitted if
The cords are P.V.C. sheathed, affording protection to the conductors against
wear and condensation. All cord ends are firmly secured so that the terminations
are not subject to stresses. The colour of the cords match that of the
Special insulation is included so that the telephone can be used in any climate.
The design provides both adequate ventilation against humidity and protection
against the ingress of insects.
Case and handset moulded in A.B.S. high-impact plastic. Four colours
available: black, dual green, dual grey, and white.
PVC-covered cadmium-tinsel-conductor cords, colour to match telephone. Held
in position by grommets which relieve conductors of any stresses.
Line cord: straight, 135 cm (54 in).
Handset cord: coiled, 25 cm (10 in) unextended; 170 cm (68 in) extended.
Articulated trigger type speed: 10 p.p.s.
Break-to-make ratio: 2 to 1.
Moulded plastic type speed: 10 p.p.s. or 20 p.p.s.
break-to-make ratio: 2 to 1.
can be varied to suit the Administration.
Single coil, d.c. resistance 1250 Ohms.
Impedance 20000 at 25 c/s, 220000 at 1000 c s.
Accepts ringing current supplies of between 16 and 30 c/s. Double gong,
Suitable for use in all climates. Prevents entry of insects.
Complete telephone: 1 kg (3 lb). Handset: 280 gm (10 oz).
Taken from the GEC Catalogue Leaflet STL22A
Tel 40 production line at the Aycliffe Works