Clive Sinclair's First Products Were Transistors

Sinclair, TI and Philco Transistors
Clive Sinclair formed Sinclair Radionics in 1961, having a good understanding of electronics and transistor manufacturing. Always the entrepreneur, he bought a quantity of transistor test failures from Semiconductors Limited (Semics) of Swindon. As seems to be the norm in British semiconductor history, it was convoluted. Semics was actually Plessey who had licensed Micro Alloy Diffused Transistor technology from Philco in the US. Sinclair used the transistors in a very small pre-amplifier and sold both the amplifier and retested/re-badged transistors separately.
Later on he must have done this again as ST140 and ST141 transistors were on the market, albeit probably in relatively small quantities again.
Above left is an ST140 Sinclair transistor. There is also an original Philco MADT transistor on the right. In the middle is a UK manufactured Texas Instruments transistor.
Texas Instruments opened a semiconductor plant in Bedford, UK in 1960 to manufacture transistors, before moving onto standard logic during the 1960s. It eventually closed in 1994. Sinclair became a large customer for TI in the UK through its various Hi-Fi, micro TV and other products including for the supply of custom ICs. Unfortunately the supply of the custom ICs was problematic and Sinclair went back to standard logic for the ZX80 home computer and Ferranti ULAs for the ZX81 and ZX Spectrum.

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