Siclair Microvision (1977)

Summary

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...