Sinclair Radionics Ltd was a company founded by Sir Clive Sinclair in Cambridge, England which developed hi-fi products, radios, calculators and scientific instruments. History After raising funds to start the business by writing articles for Practical Wireless magazine, and borrowing £50, Clive Sinclair founded Sinclair Radionics Ltd. on 25 July 1961. Sinclair initially worked alone in the evenings in a room in London (he was still a technical journalist during the day), selling radio kits by mail order. Radios and Hi-Fi Radionics initially developed hi-fi equipment; it released its first product, the Sinclair Micro-amplifier, in December 1962. The assembly and distribution of this product were contracted out to Cambridge Consultants. In 1963 Sinclair Radionics introduced their first radio with the "Sinclair Slimline" in kit form at forty-nine shillings and sixpence (£2.47½). A year later, in 1964, Sinclair released the "X-10" amplifier, one of the first commercial Class-D amplifiers. In the same year, Sinclair released the "Micro-6", matchbox-size radio, which the company claimed was the "world's smallest radio"—it could also be worn on your wrist with the "Transrista". In 1965 the "Micro-FM" debuted as "the world's first pocket-size FM tuner-receiver", but was unsuccessful due to technical difficulties. Despite problems, illegal clones were produced in the far east. Sinclair's final 1960s radio kit was the 1967 "Micromatic", billed as "the world's smallest radio" like Sinclair's earlier radios. The "Micromatic" was a reasonable success and was sold until 1971. In May 1971 Sinclair Radionics made £85,000 profit on £563,000 turnover; the following year profit increased to £97,000 on turnover of £761,000. In 1966, Sinclair Radionics re-entered the hi-fi market with the "Stereo 25", a low-cost pre-amp control system. Production was halted in 1968 due to low supply of transistors which had been purchased in 1964 as rejects from other manufacturers. In 1969 it was replaced by the "Stereo Sixty". This soon became Sinclair's most successful audio product, being the second product of the "Project 60" range. The "Project 60" products sold well and were supplemented by the "Project 605" kit in 1972. It was eventually superseded by the more advanced "Project 80" kit in 1974. In May 1973 Sinclair Radionics generated £1.8 million turnover. The last Sinclair Radionics hi-fi product was the System 4000, in 1974. Another Sinclair Radionics product that was introduced in 1964 and failed was the first class D amplifier kit rated at 10 watt RMS: a class D switching