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Electronic telex encryptor - not in collection

TC-534 was one of the first fully electronic devices for the encryption and decryption of tele­type­writer traffic (telex), developed around 1964 by Gretag AG in Regensdorf (Switzerland). Intended for use by the Swiss Army, it was the first device (and arguably the only one) that used in-house developed digital building blocks. It was later redesigned with modern TTL Integrated circuits [1].

The TC-534 was housed in two same-size watertight military containers, which allowed easy transportation and operation in a mobile environment. The image on the right shows an operational TC-534 (left) connected to a typical Siemens T-100 teletypewriter (centre) of the era.

The TC-534 is one of the first fully electronic cipher machines made by Gretag, and marks the transition from (electro)mechanical devices to electronic ones, built – in line with the industry – with the latest transistor technology of the era.
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As much of an electronic cipher machine evolves around digital circuits, it was decided to develop complete pre-assembled digital building blocks — the co-called Gretag Bausteinsystem — that would shorten the precious development time and improve the serviceablilty of the machine.

The image on the right shows one of the circuit boards of the TC-534, which holds no less than 18 of such circuit blocks. In 1964, a patent for their construction and manufacturing was filed in Canada, with a priority date of 5 December 1963. Kurt Ehrat and Dieter Eckstein were listed as the inventors, acting on behalf of Gretag [2].

In order to generate some return on investment, Gretag decided to make this technology available to other manufacturers — as OEM parts — but it remains to be seen whether this was successful.
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By the time the technology became available, the well-known 7400-series TTL Integrated Circuits (ICs) had been introduced, and it became clear that that was the way forward. Furthermore, other manufacturers – like Philips – already had similar building blocks on the market for several years and was better equipped for their distribution. The TC-534 was later redesigned with TTL ICs.

THIS PAGE IS A STUB — This page currently acts as a placeholder for future information about the TC-534. If you have additional information, please let us know.

  1. TC-534 leaflet
    Date unkown, but probably 1966.

  2. TC-534 brochure
    Gretag, December 1966.
  1. Gerhard Sulger Buel, TC-803, documentation and background information
    Personal correspondence, June 2013.

  2. Canadian Patent 760,652, Method and jig for assembling ... module
    Filed 2 December 1964 by Kurt Ehrat and Dieter Eckstein on behalf of Gretag AG.
    Issued 13 June 1967. Priority 5 December 1963.
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