SOUND POWERED TELEPHONES
These tough long-life TMC telephones are completely
self-contained - they need no battery supply
TMC sound-powered (battery less) telephones are sturdy
instruments capable of giving long service in locations where telephones
are exposed to the toughest conditions.
Originally developed by the Marine Department of Telephone Manufacturing
Company Limited for use aboard ship, their design and construction have
proved them ideally suitable for a variety of applications under equally
exacting conditions ashore. Telephones of these types have been supplied
extensively by TMC for use in mines, tunnel excavations, oilfields,
shipyards and building sites.
As TMC sound-powered telephones are self-energizing and
completely independent of battery or mains supplies they are easily
transportable, simple to operate, require the minimum attention and can
be installed immediately in any location.
L33 - Sound Powered Ship Phone
This telephone comprises a sound-powered handset, fitted to a
compact mounting. The handset is a navy model AP 13220.
The handset is held firmly in place by locating pins and a large
spring. For more pictures click
here L45 - Bulkhead telephone
Wall mounted telephone marketed as noise proof. This has an
additional receiver.
L50 & L50A - Bulkhead Telephone (shown to the
right)
 L50
comprises a sound-powered handset, hand operated calling generator and a
howler calling unit in a non-corrodible cast aluminium alloy weatherproof
case with a pleasing grey hammered finish. It is designed for use where a
really robust type of telephone is required.
L50A as type L50, but fitted with a switch operated by a handset cradle. It
is intended for connection as an outstation with intercommunication type
telephones L76 and L77. For use in extremely noisy situations these bulkhead
telephones can be fitted with an extra receiver for an additional charge.
L50A - (taken from undated document)
as type L50, but fitted with a switch operated by a handset cradle. It
is intended for connection as an outstation with intercommunication type
telephones L70, L71, L76 and L77. A 4-core cable is required for connection.
L50C - (taken from undated document)
Is similar to type L50 but includes an indicting lamp, making it
suitable for use where more than one instrument is installed at the same
location. The lamp lighting while the generator at the calling station is
operated to indicate the instrument being called.
Both L50 and L50C telephones are suitable for use as direct
working pairs, or alternatively for working with each other or types L74,
L75 and L79. A 3-core cable is required for connection.
L50D - (taken from undated document)
Is similar to type L50A, but connected internally to permit working over
2-wires. The type is suitable for use as direct working pairs, or for
working with instrument L51.
L50E - (taken from undated document)
Also similar to type L50A, but connected internally to permit working
over 3-wires. It is primarily for use where parallel working of up to
a maximum of six telephones is required (a system of `code ringing' is
necessary for this type of installation).
For use in extremely noisy situations any of these bulkhead telephones can
be fitted with an extra receiver for an additional charge.
L51 - Portable Telephone
 The
sheet-metal case is fitted with a webbing carrying strap and contains a
sound-powered handset, high frequency calling generator and thumb-screw line
connection terminals. Incoming calling signals are received as a 'hoot on
the sound-powered insert units in the handset.
L51 - Portable Telephone (taken from undated document)
This instrument is ideal for temporary installation in railway marshalling
yards, mines rescue operations or building sites, etc. The sheet-metal case
is fitted with a webbing carrying strap and contains a sound-powered
handset, high frequency calling generator and thumbscrew line connection
terminals. Incoming calling signals are received as a `hoot' on the
sound-powered insert units in the handset.
Two wires, with a maximum loop resistance of 300 ohms, are required for connection between instruments.
L60 - Intercommunication Bulkhead Telephone
This telephone is suitable for use where communication is required to
two or more outstations, and comprises a sound-powered handset, hand
operated calling generator, howler calling unit and a 12-position switch
providing selective calling and speaking to a maximum of eleven outstations.
L61 - Bulkhead Telephone
Telephone used with the L60 model.
L64 - Bulkhead Telephone
 This
weatherproof telephone has a hand telephone set with a spiral cord and
is totally enclosed by a hinged snap-shut lid when not in use. It has a
ferrous alloy case.
It was specially designed for the National Coal Board using a separate
safe signalling system supplied by N.C.B.
L70 - Intercommunication Cabin Bulkhead Telephone (taken from undated
document)
This telephone is intended for use where communication is required to
two or more outstations and comprises a sound-powered handset, hand operated
calling generator, buzzer and a 12-position switch providing selective
calling and speaking to a maximum of eleven outstations. The smart black
Bakelite case makes it suitable for use in ship's cabins, etc., and it can
be interconnected to other telephones of the same type or to types 30A, L71,
L72, L73, L76, L77 and L78.
The number of conductors between
telephones is dependent upon the system required and, if you wish, TMC will
advise you of the correct number needed for your installation.
L71 - Intercommunication Cabin - Telephone for Desk Use (taken from
undated document)
This telephone possesses exactly the same facilities as the L70 and has
a similar finish. It is for desk use. L72 - Single Way Cabin
Bulkhead Telephone (taken from undated document)
Is similar to type L74, but fitted with a switch operated by a handset
cradle. It is intended for connection as an outstation with
intercommunication type telephones L70, L71, L76 and L77. A 4-core cable is
required for connection. L73 - Single Way Cabin Bulkhead
Telephone (taken from undated document)
As L75 but fitted with a switch operated by a handset cradle and
suitable for connection as an outstation with intercommunication type
telephones L70, L74 - Single Way Cabin Bulkhead Telephone
(taken from undated document)
Comprises a sound-powered handset, hand operated calling generator and
buzzer - and, like the L70, it has a smart black bakelite case. This type is
suitable for use as direct working pairs, or alternatively for working with
instruments L50, L50C, L75 and L79. A 3-core cable is required for
connection. L75 - Single Way Cabin Bulkhead Telephone (taken
from undated document)
L75comprises a sound-powered handset, hand operated calling generator
and buzzer in a black bakelite case and is suitable for use as direct
working pairs, or alternatively for working with instruments L50, L50C, L74
and L79. A 3-core cable is required for connection.
For L71, L76 and L77: a 4-core cable is required for connection.
L76 - Intercommunication Bulkhead Telephone
This telephone is suitable for use where communication is required to
two or more outstations, and comprises a sound-powered handset, hand
operated calling generator, howler calling unit and a 12-position switch
providing selective calling and speaking to a maximum of eleven outstations.
The non-corrodible, cast aluminium-alloy weatherproof case with grey
hammered finish makes it a really robust instrument and it is intended for
connecting to other telephones of the same type or to types L50A, L77 & L78.
L76 - Intercommunication Bulkhead Telephone (taken from undated document)
This telephone is suitable for use where communication is required to
two or more outstations, and comprises a sound-powered handset, hand
operated calling generator, howler calling unit and a 12-position switch
providing selective calling and speaking to a maximum of eleven outstations.
The non-corrodible, cast aluminium-alloy weatherproof case with grey
hammered finish makes it a really robust instrument and it is intended for
connecting to other telephones of the same type or to types L50A, L70, L71,
L72, L73, L77 and L78.
The number of conductors between telephones is dependent upon the system
required and, if you wish, TMC will advise you on the number required for
your installation. For use in extremely noisy situations an extra receiver
can be fitted at an additional charge.
L77 - Intercommunication Bulkhead Telephone for Portable
& Bulkhead mounting
L77 comprises a sound-powered handset, hand operated calling generator,
howler calling unit and a 12-position switch providing selective calling and
speaking to a maximum of eleven outstations. The non-corrodible, cast
aluminium-alloy weatherproof case with snap-shut lid makes it suitable for
the most exposed positions. It is intended for connecting to other
telephones of the same type or to types L50A, L76 & L78.
Intercommunication Bulkhead Telephone for Portable &
Bulkhead mounting L77 (taken from undated document)
L77comprises a sound-powered handset, hand operated calling generator,
howler calling unit and a 12-position switch providing selective calling and
speaking to a maximum of eleven outstations. The non-corrodible, cast
aluminium-alloy weatherproof case with snap-shut lid makes it suitable for
the most exposed positions and all components are mounted on the inner
cover, which is removable as a unit from the case, permitting easy access
for maintenance purposes. It is intended for connecting to other telephones
of the same type or to types L50A, L70, L71, L72, L73, L76, and L78.
L77A - Intercommunication Bulkhead Telephone for Portable &
Bulkhead mounting (taken from undated document)
Is a portable version of type L77 supplied with 8ft. C.T.S. cable, with W.T.
plug and socket, hooks for deck rails and a brass carrying handle.
L78 - Single Line Hood Telephone for Portable and
Bulkhead mounting
As type L79 but fitted with a switch operated by a handset cradle. It is
intended for connection as an outstation with intercommunication type
telephones L76 & L77.
L78 - Single Line Hood Telephone for Portable and Bulkhead
mounting (taken from undated document)
As type L79 but fitted with a switch operated by a handset cradle. It is
intended for connection as an outstation with intercommunication type
telephones L70, L71, L76 and L77. A 4-core cable is required for connection.
L78A - Single Line Hood Telephone for Portable and Bulkhead
mounting (taken from undated document)
Is a portable version of type L78 supplied with 8ft. 4-core C.T.S.
cable, 4-pin W.T. plug and socket, hooks for deck rails and a brass carrying
handle. L79 - Single Line Hood Telephone for Portable and Bulkhead
mounting
Is a single line version of type L77 and is suitable for use as
direct working pairs, or alternatively for working with L50. A 3-core cable
is required for connection. L79 - Single Line Hood Telephone for Portable and Bulkhead
mounting (taken from undated document)
Is a single line version of type L77 and is suitable for use as direct
working pairs, or alternatively for working with instruments L50, L50C, L74
and L75. A 3-core cable is required for connection. If required for
extremely noisy situations an extra receiver can be fitted at an additional
charge. L79A - Single Line Hood Telephone for Portable and Bulkhead
mounting (taken from undated document)
Is a portable version of type L79 supplied with 8ft. 3-core C.T.S.
cable, 3-pin W.T. plug and socket, hooks for deck rails and a brass carrying
handle. L81 - Single Line Hood Telephone for
Bulkhead mounting - Automatic 
L82 - Single Line Hood Telephone for
Bulkhead mounting - CB 
Accessories
L87 -
High Frequency Relay Type
The high frequency relay has been designed to operate in conjunction with
TMC sound-powered instruments in locations where external noise necessitates
a loud-sounding bell, re-entrant horn or rotating beacon to supplement the
howler incorporated within the telephone itself.
Loud Sounding Bell
For systems where the call unit of telephone is not sufficient to
overcome the level of background noise. Operates in conjunction with H.F.
relay; a.c. or d.c. Various sizes available.
Rotating Beacon
For the location which has a high level of background noise, the
rotating beacon can be fitted to give a visual calling signal. For ships'
engine rooms, workshops, etc.
Re-entrant Horn
Type 'A' Re-entrant Horn. Fitted with a TMC Sound-Powered Unit, this is
a medium sized horn giving a loud calling signal in situations with a high
ambient noise level. Either standard mounting brackets or gimbal and spigot.
Dimensions of TMC Sound-Powered Telephones
(1966 models)
| Model |
Width |
Height |
Depth |
Weight |
| L50 & L50A |
7.5 in. (19 cm.) |
11.5 in. (29 cm.) |
7.5 in. (19 cm.) |
13 lb. (5.9 kg.) |
| L51 |
5 in. (12.7 cm.) |
5.5 in. (14 cm.) |
11.25 in. (26 cm.) |
8.75 lb. (4 kg.) |
| L64 |
9.75 in. (24.5 cm.) |
13.1 in. (33.5 cm.) |
6.5 in. (16.5 cm.) |
28 lb. (12.7 kg.) |
| L76 |
8.5 in.(21.6 cm.) |
11.5 in. (29.2 cm.) |
8 in. (20.3 cm.) |
15 lb. (6.8 kg.) |
| L77 |
10.5 in. (26.7 cm.) |
16.5 in. (41.9 cm.) |
7.5 in. (19 cm.) |
21.5 lb. (9.8 kg.) |
| L78 & L79 |
10.5 in. (26.7 cm.) |
16.5 in. (41.9 cm.) |
7.5 in. (19 cm.) |
21 lb. (9.5 kg.) |
TMC sound-powered telephones comply with Ministry of Fuel and Power
Certificates covering up to group II of intrinsically safe requirements.
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