November_1970 — Page 45

materials and equipment

DOOR CLOSER

A new electromagnetic mechanism ensures the automatic closure of doors in the event of a fire warning. Com. prising a wall-mounted electromagnet and a self-aligning door-striker plate, the device normally operates to hold the door open, the loss of an electrical supply causing the door to swing shut.

The wall-mounted assembly mea- sures 5 x 4 x 14 in. deep and is avail- able in two versions: one for use with a 240 v a.c. supply, the other for use

and 4 ft. long, with a selection of frameless, flush-framed and regressed framed diffusing panels.

The fixtures have a recessed depth of only 4 in., and offer a wide selec-

degree of penetration is required, such as building sites. Transmitter output is approximately 500 mW, with a 14-dB signal; noise ratio, receiver sensitivity is 0.75 microvolts and operating ranges of over 10 miles have been achieved under favourable conditions.

The unit's 12.5 v nickel-cadmium battery has an endurance of ten hours under normal transit/receiver condi- tions. Loudspeaker/microphone assem- blies include a conventional hand mi- crophone, the helmet set, a telephone handset and a 'muffling' handset with boom or throat microphone for use in noisy conditions.

A 6 in. flexible aerial, used when the equipment serves as a walkie- talkie, can be removed for connection to an external aerial when using the set in a vehicle or as a fixed station. Single-channel operation requires only an on/off/volume switch on the trans-

BE

LI

Magnetic retainer for wall mounting and self- aligning door striker plate

with a 24 direct current. In both cases the current is fed to a high-resis- tance solenoid wound around a soft- iron core.

This forms a powerful electromag- net consuming approximately 40 ma. A stainless-steel disc acts as the front panel of this unit, while the other soft- iron assembly is screwed on to the door in alignment with the face of the solenoid core, an integral swivel joint ensuring good magnetic coupling.

The mechanism thus holds the door open magnetically against the force of its return springs until a fire- detection system cuts off the mains or d.c. supply in the event of a fire, allowing the door to swing shut.

The makers are AES Emergency Systems Ltd., 120 High Road, London, N.15.

LIGHTING FIXTURE

A new line of lighting fixtures that are specially designed for easy installa- tion has been introduced by Sunbeam Lighting Co., Inc., 777 E 14th Place, Los Angeles, Calif. 90021.

Known as the Sunbeam 79200 re- cessed series, the line comprises 2 ft. wide lay-in recessed luminaires, 2 ft.

Far East BUILDER, November 1970

Sunbeam fixture for grid ceiling

tion of prismatic and translucent diffu- sing panels, and two or four-lamp con- figuration. The diffusing panels in the fixtures are of the lift and shift type which automatically self-centre when closed, and hinge from either side for convenience of maintenance.

Quick wire devices allow flex con- nections from the top without remov ing the fixture wireway cover. Also, the 2 ft. x 2 ft. units have a built-in provision to allow for the relocation of lamp sockets in the field to accom- modate 6 in. or 3 5/8 in. U-shaped lamp leg spacing.

RADIO TELEPHONE

Type BE 357 Mk.2 personal UHF radio telephone offers a range of easily interchangeable speaker/microphone assemblies to overcome local noise problems, and a removeable aerial allows it to be switched from a walkie- talkie role to use as a vehicle or fixed- station set. The illustration shows an industrial-helmet transducer assembly designed for use on building sites.

The equipment is particularly suit- able for screened areas where a high

Radio telephone for building sites ceiver unit and a press-to-transmit but- ton on the loudspeaker/microphone assembly.

The makers are Burndept Electro- nics (ER) Ltd., St. Fidelis Road, Erith, Kent, UK.

METRIC CONVERSION

The Cosmorule metric converter operates on the slide-rule principle and comes in two different models to pro- vide a comprehensive range of conver- sions.

Each model is based on a small plastic frame, designed to accept two sliding rules, set side by side within its main body, and two printed cardboard fascias, one on each side. Slots in the frame and corresponding cut-outs in the fascia panels make it possible for the sliding rules to be read from both sides of the converter.

The fascia panels, printed on both

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