Ferranti Semiconductors This page ©2008 Andrew Wylie all rights reserved

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The British company Ferranti Ltd, which closed down in 1994 after over 100 years of operation, was an electrical engineering company with a long history of working on government and military contracts. They manufactured a large number of silicon transistors and diodes for use in such projects. Because of the secrecy surrounding such work, these components are less well-known than other UK manufacturers' semiconductors, although Ferranti databooks are not too hard to find. The ones that I possess start in 1960, but I do not know the details of their manufacturing capability, nor why they made no germanium devices. They seem to have started with quite a comprehensive range of devices.

If you know anything about Ferranti's semiconductor history, please

I do not possess all the transistors below, in fact I am seeking many of them. It is noted in the text where I am seeking examples of any particular type: if you have some for sale or exchange, please Conversely, I am happy to help anyone looking for information on these devices. I have an extensive collection of original data sheets and books, and can provide some information on many Ferranti types.

Most Ferranti semiconductors are painted black, and bear just a letter F to indicate the manufacturer. Ferranti devices were all silicon, and nearly all used standardised encapsulation. This ZT23 transistor is a silicon NPN mesa transistor, for low-leakage general purpose applications. It dates from about 1961. The 'Ferranti Silicon Semiconductor Devices' booklet from 1962 shows five devices in this range, ZT20 - ZT24, with two different Vce max values, and different gain banding.

Here is a box of ZT43 transistors in unpainted TO-18 cans. The ZT43 transistor is a silicon NPN general purpose type from about 1962. The 'Ferranti Silicon Semiconductor Devices' booklet from 1962 shows five devices in this range, ZT40 - ZT44, with two different Vce max values, and different gain banding.

The 'Ferranti Silicon Semiconductor Devices' booklet from 1962 shows five other ranges of transistors, but I have never seen a specimen of any of them. They are: ZT696, ZT697 and ZT1420 are medium-power general-purpose NPN types in TO-5 cans ZT706, ZT708 and ZT1708 are planar NPN types in TO-46 cans ZT1479 to ZT1482 are medium-power diffused-junction NPN types in TO-5 cans ZT1483 to ZT1486 are intermediate-power diffused-junction NPN types in TO-8 cans ZT1511 to ZT1514 are high-power diffused-junction NPN types in TO-36 cans If you have some for sale or exchange, please

Because Ferranti were involved in many contracts with the UK military, it is not surprising that they produced many CV series devices. This is a box of CV7154 transistors date-coded 1964. The type CV7154 is equivalent to the ZT43 above. The 'Ferranti Silicon Semiconductor Devices' booklet from 1962 shows fifty-seven CV equivalents to Ferranti devices.

Ferranti diodes are more common than their transistors. This KS67 is a 9 volt Zener, unusual for its TO-5 packaging.

The ZS74 is a medium power rectifier diode. It is unusual because Ferranti produced relatively few types in an axial package.

The commonest Ferranti device shape is a characteristic small black can with two leads at the same end. This is used by various series including the ZS junction diodes and the KS Zener diodes.