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History of the manufacturer  

Sinclair Radionics Ltd.; St. Ives (Cambridge)

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Name: Sinclair Radionics Ltd.; St. Ives (Cambridge)    (GB)  
Abbreviation: sinclair
Products: Model types Tube manufacturer

Sinclair Radionics Ltd.
London Road, St. Ives, Huntingdon, Cambridge

Sinclair Radionics Ltd is a consumer electronics company founded by Sir Clive Marles Sinclair ( 1940– 2021) in Cambridge, England on 25 July 1961. 

They manufactured hi-fi equipment, calculators, radios, and other products. In 1966 Sinclair created but never sold the world's first pocket television.

In 1972 they marketed the world's first pocket calculator, the Sinclair Executive. Many other pocket calculator variants followed including the Sinclair Cambridge, the Sinclair Scientific, and the Sinclair Oxford.

In the 1980s Sinclair entered the personal computer market with the ZX80, at the time the cheapest personal computer for sale in the UK. In 1982 the ZX Spectrum was released, later becoming Britain's best-selling computer, competing aggressively against Commodore and Amstrad. At the height of its success, and largely inspired by the Japanese Fifth Generation Computer program, the company established the "MetaLab" research centre at Milton Hall (near Cambridge), in order to pursue Artificial Intelligence, Wafer Scale Integration, formal verification, and other advanced projects.

Founded: 1961
Production: 1958 -

As a teenager in the late 1950’s Clive Sinclair published several radio projects in Practical Wireless, like the 1958 Micro-Midget. He also published Practical Transistor Receivers Book 1, in 1959 and in 1962 Modern Transistor Circuits for Beginners.

He founded Sinclair Radionics Ltd. on 25 July 1961.

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 they introduced their first radio with the Sinclair Slimline in kit form at forty-nine shillings and sixpence.

A year later, in 1964, Sinclair released the X10 amplifier, one of the first commercial Class-D amplifiers. In the same year, Sinclair released the Micro-6, matchbox-sized radio, which the company claimed was the "world's smallest radio", it could also be worn on your wrist.


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 the 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 amplifier that was good in theory but sadly ahead of its time and available technology. The amplifier used low-frequency germanium transistors as pulse-width modulators and switches and wrongly relied on the loudspeaker's inductance to filter the class D signal into audio. Most often this would short out the output transistors. When it did work the power level was far below 10 watts and Sinclair's main advertising channel, Wireless World magazine, was so deluged with complaints that it supposedly refused to take further advertisements from Sinclair.

Sinclair Radionics launched the System 2000 amplifier, FM tuner and loudspeaker in 1968. followed by System 3000 in 1972.

Calculators and test equipment

In 1972, Radionics launched its first electronic calculator, the Executive, which was considerably smaller than its competitors by the use of hearing-aid-sized batteries. What had made this possible was it had been discovered that there was considerable latency in the display and memory and that, with the addition of a timer, power could be withheld from these battery-draining components for much of the time, thus greatly extending battery life.



During the majority of the 1970s, Sinclair focused on building the most affordable pocket calculators with the best design. In 1972 Sinclair released the world's first slim-line pocket calculator, the Sinclair Executive, for £79.95. The calculator only included basic maths functions, and the LED display required much power. It is often credited as being the world's first attractively styled calculator that did not require mains power to be used like prior calculators. The Executive was a phenomenal success, earning Sinclair £1.8m in profit. In 1973 the slightly larger Sinclair Cambridge was introduced at a far cheaper price of £29.95 + VAT. A cheaper Executive was also launched shortly after. In addition to expanding the Cambridge range, the Sinclair Scientific was launched in 1975. It was a scientific pocket calculator for a very competitive price of £49.95. In 1977 a revised model, the Scientific Programmable, was released at £29.95.[6] The Scientific Programmable Mark 2 was later released, reducing the price to £17.22.

In 1975, Sinclair Radionics launched the Oxford range of briefcase calculators. Sinclair also attempted to capture the top-end calculator market with the Sinclair Sovereign, available in plated gold or silver. The calculator was critically acclaimed for its excellent engineering and design and enjoyed short success. Final attempts at the mass market for calculators, the Sinclair Enterprise and the President, did not sell well.

In 1974, Radionics launched the DM1 digital multimeter. Such scientific instruments were to form a quiet backbone of Radionics business for the rest of its existence. In marked contrast to the rest of the Sinclair range, the instruments gained a reputation for reliable conventionality rather than often unreliable idiosyncrasy.

Black Watch

In August 1975, Sinclair introduced the Black Watch digital watch at £17.95 in kit form and £24.95 ready-built, although this wasn't available to buy until January 1976. Including a five-digit LED display, it suffered from technical flaws related to the design of the case, the chip, the battery, and its accuracy. Not only was the watch unreliable, but Radionics was also not able to fulfill the orders it had taken. As a result, Radionics made its first loss in the financial year April 1974 – April 1975. The Black Watch fiasco had a devastating effect on Sinclair's finances, and the company would have gone bankrupt had not the Government, through the National Enterprise Board, stepped in to support it.

Portable televisions

In 1966, Sinclair Radionics developed the world's first portable television, the Microvision, but never attempted to sell it because development costs would have been too high based on the complicated design the Microvision used.

In April 1976, the National Enterprise Board bought a 43% stake in Sinclair Radionics for £650,000, and in October the National Research and Development Council agreed to provide £1 million for a revived portable TV project, which was finally launched in January 1977 as the Microvision TV1A and MON1A at £99.95. Supply exceeded demand, and 12,000 units were left unsold until they were sold off cheaply. This resulted in a £480,000 loss for Sinclair. Sir Clive Sinclair was certain that the TV1B model released in 1978 would be more successful, but sales were disappointing.



In July 1977, the NEB increased its stake in Radionics to 73%. By June 1978 Sinclair Radionics was working on the NewBrain microcomputer project, which was later taken over by Newbury Laboratories.

In May 1979, the NEB announced that it intended to sell Radionics' calculator and TV interests; they were bought by the ESL Bristol group (as Radionic Products Ltd.) and Binatone respectively. In July Clive Sinclair resigned with a £10,000 golden handshake. In September the NEB renamed what was left of Radionics (i.e. the scientific instrument business) as Sinclair Electronics Ltd.; in January 1980 this was changed to Thandar Electronics Ltd. In 1989, Thandar Electronics Ltd merged with Thurlby Electronics Ltd, forming Thurlby Thandar Instruments Ltd. This company now does business under the name Aim and Thurlby Thandar Instruments (Aim-TTi).

Sinclair Instrument and Science of Cambridge

When it became clear that Radionics was failing, Clive Sinclair took steps to ensure that he would be able to continue to pursue his commercial goals: in February 1975, he changed the name of Ablesdeal Ltd. (an off-the-shelf company he bought in September 1973, for just such an eventuality) to Westminster Mail Order Ltd.; this was changed to Sinclair Instrument Ltd. in August 1975.

Finding it inconvenient to share control after the NEB became involved in Radionics, Sinclair encouraged Chris Curry, who had been working for Radionics since 1966, to leave and get Sinclair Instrument up and running.

Sinclair Instrument developed the Wrist Calculator to generate cash, which soon became a commercial success selling in surprising figures. In July 1977 Sinclair Instrument Ltd was renamed Science of Cambridge Ltd. Around about the same time Ian Williamson showed Chris Curry a prototype microcomputer based around a National Semiconductor SC/MP microprocessor and some parts taken from an earlier Sinclair calculator. This was sold as the MK14 microcomputer kit. Science of Cambridge ultimately became Sinclair Research Ltd.

Wikipedia accessed March 2022

This manufacturer was suggested by Mario Tieke.

Some models:
Country Year Name 1st Tube Notes
GB  70 Micromatic MK2 ME4102  Bausatz, bestehend aus 20 Teilen Micromatic MK1 has 3 transistors, MK2 has 2 transistors. ... 
GB  77 Micro Vision MTV1 MTV1A D5-100W  Sinclair MTV1 (MTV1A); First European pocket b/w TV set, 2" Telefunken CRT; Multist... 
GB  78 Low Power Portable Oscilloscope SC110 D5-100W  32 × 26 mm screen portable oscilloscope. 0-10 MHz; 10 mV/div to 50 V/div in 12 ranges. Als... 
GB  83 FTV1 FTV1  Nur UHF, Videostandards: 525/625 Zeilen. Audiostandards: 4,5/5,5/6,0 MHz Ton-ZF.Die flache... 
GB  78 MTV1B D5-100W  UHF, britische TV-Norm. There are 12 transistors (excluding tuner) and 4 IC's 
GB  65 Micro FM AF178  Bausatz für Miniatur-FM-Empfänger, sehr einfacher Superhet, aperiodische RF-Verstärker, se... 
GB  81 Video Monitor MON 1A D5-100W  Sinclair - Thander MON 1A, Video Monitor; 5 cm b/w CRT, BNC in, 525 and 625 lines, 600 mW... 
GB  67 Micromatic MK1   3 Transistors in reflex circuit provides 2 RF stages & 3 AF stages. 2 Diodes used for demo... 
GB  58 Micro-Midget   A midget transistor design by Sinclair, published in the Practical Wireless magazine, Nov ... 
GB  63 Slimline MAT121  2 Transistors provide 1 RF stage with fixed reaction, & 2 AF stages by use of refle... 
GB  64 Micro 6   3 Transistors in reflex circuit provides 2 RF stages & 3 AF stages. 2 Diodes used for demo... 
GB  85 FM Watch Radio FMWR   Sinclair FM Watch Radio FMWR.Combination of a LCD digital wristwatch with alarm function a... 


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