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Sinclairbs Microvision. Sinclair say the final assembly 'requires only the connection of four printed circuit boards, insertion and connection of the tube, and housing the whole in a three-piece black steel case.' The circuit uses 300 transistors. The heater needs 15s to warm up as a contribution to its low power consumption.
After years of rumour and many confident predictions that next year would see the launch, Clive Sinclair showed his 2 in television receiver to a large collection of professional cynics - the press - on Monday, January 10.
Let it be said at once that the Microvision is a remarkable piece of design. Most of the components, including three of the five integrated circuits and the tube, were developed for the receiver, which measures 6 × 4 × 1½ in. It is most certainly not a toy - with a £200 price tag it is certainly free of that connotation - since most of the design compromises appear to have been made.with low power consumption in mind.
The tube was developed by AEG Telefunken, who based their development on a design by A V de V Krause (Wireless World, July 1974, p.259). The screen diagonal is 2 in, and the tube length about 4.5 in. Electrostatic deflection is used to reduce power consumption. The EHT is about 2 kV, derived from an oscillator which provides barely acceptable brightness. (We were not able to look at the picture out of doors because the Sinclair staff seemed so nervous that some acquisitive scribe might make off with the set that we weren't allowed to hold it, let along go outside with it.) Sinclair were unsure of the heater power - at one time the Krause tube consumed 30 mW - but that of a similar AEG Telefunken tube advertised in German and Danish magazines is quoted as being 35mW.
Sinclairbs notion that the receiver could be of use to travelling business-men is supported by the flexibility of tuning and standards. The own-design bipolar tuners cover Bands I, III, IV and V with the aid of p-i-n diode switching and varicap-diode tuning. Line standards of 625 and 525 at field rates of 50 or 60 Hz are provided, with IF selection of 4.5, 5.5 or 6MHz. Tuner sensitivity, assisted by separate, folding VHF and UHF aerials, was good enough to give a reasonable picture in the steel-framed Savoy Hotel. Gated AGC and AFC are included, as is flywheel sync.
Sinclair decided to use two SGS i.c's for sound IF and 50 mW audio output, but vision functions are performed by three chips designed by Sinclair and a further 20 transistors. Attention to power-saving in the design has yielded a truly amazing consumption of 750 mW from 4.8 V. Four 1.2 V rechargeable cells are used. These last four hours but an external AC adaptor will charge them and run the set as well. A 40-hour battery pack can be used, as can a car battery, which will also charge the internal cells.
It may be said that the size of the picture is too small for comfortable viewing. It is little bigger than a 35 mm slide, which is usually projected or seen through a magnifier. Sinclair say that 2 in was selected after tests with many people and point out that 2 in at a viewing distance of a foot - the distance they say, at which most people read a paperback book - is equivalent to a 24 in screen 12 feet away, provided that the spot size is reduced to enable the resolution of the big picture to be retained, which they claim to have done.
However, the angle subtended at the eye is not the only important measurement. Normally two eyes will be used, and the way they converge, together with apparent size, is part of the process which gives the viewer an appreciation of distance. The brain will recognise a big picture, placed farther away than a small picture, as being bigger than the small one and will automatically assume that the bigger one is more detailed, even though it may not be. C Burns, in an article in Wireless World in January 1953, pointed out that a magnifying lens not only increases the subtended angle but makes the screen look farther away, thereby adding to the apparent increase in size. Sinclair have probably considered the use of a lens, but if so they made no mention of one as an accessory.
The scepticism which has arisen as a result of the previous frequency of false alarms about the Sinclair set's imminent appearance in the shops was compounded by the secrecy which still surrounds its, production. At the Savoy press conference on January 10, Clive Sinclair said that they first started the project 14 years ago and had produced several complete receivers in that time but they all lacked something and we wanted to do it properly. We have spent £½ million of our own money to do this in research and development. Yet the National Enterprise Board, which last November took a 43% stake in Sinclair, worth an injection of another £650,000, on the basis of a three-year profit forecast on the Microvision, have not, Sinclair says, committed the company to any production schedule. He would not say when production would start, how many staff would be making them, or what the initial number made would be, yet he insisted that the sets would be in the shops 'next month'. Who would be stocking the set? He couldn't say: 'We haven't invited any orders because we haven't shown before'. He would show it to the trade first. 'Existing customers are interested in taking sets', he said. (Lasky's have since confirmed that they have ordered an unspecified number of sets for delivery when they become available. An order for the sets has been outstanding for some time.
Although he asserted that 'To the best of our knowledge nobody else is even remotely close to doing what we are doing', Sinclair added during questions that to give a production figure 'would be valuable information for our competitors'. What competitors? 'Any that care to come along'.They had had pilot models for some time, he said, and had been conducting field trials in various parts of the world since last August. 'There were dozens of sets in existence', he said. But since they would not be able to supply the demand until the middle of the year any of the £¼ million of advertising they planned would not be spent till then. Later he said he didn't know what the volume of production would be because 'we don't yet have it as a viable product'.
In one or two years time they would produce a single-standard, lower-priced model for the mass market, but the main aim was to reach the prestige, executive market, particularly in the US. Most of the current sets would be exported and it would eventually account for half Sinclair's turnover. 'The market is comparable with the market for pocket calculators, about 50 million units a year; comparable bearing in mind that it's a more expensive item'. He had 'no clear idea' what the simpler sets would cost.
In his opening remarks Sinclair said, 'We have no plans for colour. It is technologically possible but would add greatly to the cost and we can't see any justification for such an increase'. When asked later how much a colour set would cost he said, 'We can't put a figure on a colour system'. Most of the cost would be in the tube. 'We haven't looked at this in great detail. The use of a shadow mask tube would be impossible on such a small screen so it would have to be non-standard'.
The price of the black and white set has been fixed at £175 plus VAT. Sinclair says there is no prospect of a reduction. 'Firstly because it is such a complicated product and, secondly, we have a monopoly'.
With the cover removed.
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