Sinclair Research "FM Wristwatch Radio", an LCD wristwatch with a radio attached. However, the watch had several problems and never went into full production. Sinclair had long had an interest in electric vehicles, and during the early 1980s he worked on the design of a single-seater "personal vehicle", eventually starting a company called Sinclair Vehicles Ltd in March 1983. He launched the Sinclair C5 electric vehicle on 10 January 1985, but it was a commercial disaster, selling only 17,000 units and losing Sinclair £7,000,000. Sinclair Vehicles went into liquidation later the same year. The failure of the C5, combined with those of
Sinclair Sovereign use, but in reality the small button cell batteries and comparatively high power consumption meant a short battery life compared to the competition. Sinclair Sovereign The Sinclair Sovereign was a high-end calculator introduced by Clive Sinclair's company Sinclair Radionics in 1976. It was an attempt to escape from the unprofitable low end of the market, and one of the last calculators Sinclair produced. Made with a case of pressed steel that a variety of finishes, it cost between and at a time when other calculators could be purchased for under . A number of factors meant that the Sovereign was