April_1970 — Page 43

materials and equipment

JOIST

The British firm, Sanders and Fors- ter, Ltd., Cooks Road, London, E.15, are marketing a lightweight joist to replace timber in many structural functions.

Called Litebilt, the joists are made in sections of 5in. and 7in. depth and in any length up to 24ft. They can be

Litebilt joist

supplied in plain cut ends or provided with end plates for suspended fixing.

Both chords of the joist have nail- ing slits so that floorboards, sheeting or plasterboard can be fixed directly by using ordinary annular ringed nails.

JIG SAW

The operating speed on a new hand jig saw can be varied to give the best cutting efficiency on a range of dif- ferent sheet materials.

Model TR/577 jig saw

An electronic speed control as- sembly permits selection of operating speeds between 1,000 to 4,000 re- ciprocations a minute. This is said to

overcome many of the problems of cutting certain materials with a high single-speed saw p.v.c., acrylic sheet and other materials with a low melting point for example, which tend to melt and block the teeth of the saw.

The model incorporates a 320 W electric motor and a thumb-operated on-off switching arrangement. It is called the Model TR/577 and is mar- ketted by Trend Industrial Equipment Ltd., 1 Lechmere Road, London, N.W.2.

SMOKE DETECTOR

By combining photocells with in- tegrated circuitry, Photain Controls Ltd., Randalls Road, Leatherhead, Surrey, UK, have produced an inex- pensive smoke detector for use in oil- or gas-fired warm air central-heating systems. Suitable for use with new or existing installations, the unit auto matically switches off the boiler on detecting smoke in the return-air duct.

The instrument, designated the Type DSD, consists of a small cast- aluminium housing and an attached, 306-mm probe. The probe is inserted

Type DSD smoke detector

Photinia Contral

into the return-air duct to the central heater, the housing being mounted on the outside of the duct.

A low-voltage lamp is fitted at the end of the probe, and light from this lamp falls on to a light-activated switch in the control housing. Contain- ed in the control housing are a sensi- tivity control to enable each installa- tion to be set on site, the power sup- ply and an operational relay with a set of changeover contacts rated at 5 amp. 250 v a.c. resistive load. Input supply may be 110- or 200/250 v, 50/60-Hz.

a.c.

The output contacts are wired in series with the boiler-control mech-

anism so that immediately smoke ob- scures the lamp from the light-sensitive switch, the boiler is automatically switched off.

Agents in Malaysia are: Syarikat Nikko Co., Kuala Lumpur.

ELECTRICAL SWITCHES

M.K. Electric Ltd., Shrubbery Road, London, N.9, have introduced a range of white electrical accessories to match modern appliances.

Socket-outlets, 13 amps, and switch- socket outlets designed for installa- tion in lin. deep boxes with two fixing holes in a horizontal plane, and a com- plementary range of switched and un- switched spur boxes are all offered in the new colour. These accessories have

Plug with insulated sleeves

ultra shallow bases to provide ample wiring space and have MK pressure plate clamping terminals which are suitable for either stranded or solid copper conductors.

New to the range is a 13 amp fused plug incorporating insulated sleeves fixed to the current-carrying pins. This additional safety feature prevents touching the plug pins while inserting or withdrawing the plug from a socket outlet. The terminals of this new plug are positioned to enable all three flexi- bles to be trimmed to the same length for quick wiring.

3-D PICTURES

Architects who use computers may soon have a practical, fast and inex- pensive way of converting data in a computer's memory into three-dimen- sional pictures and graphs.

With a process devised at Bell Tele- phone Laboratories, 195 Broadway, New York, it takes only a few seconds of computer time to turn equations, formulas, statistical data and other in- formation into a form suitable for the making of holograms. Viewed under ordinary light, the holograms produce three-dimensional pictures that can display a full 360-degree view of the object shown.

Holography, which has been called

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