Siemens ST

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The Siemens ST is a switch from Siemens that precedes the Siemens STB "Schreibtasten" switch family; hence, it was decided to call the series ST at deskthority. We don't know the Siemens name of it.

Characteristics[edit | edit source]

80 g actuation force
keytravel 6 mm
contact crosspoint type
gold-plated
60 mΩ
typical bounce 1–2 ms, up to 30 ms
Key feel: the switch has a pronounced tactile event which Siemens called "dem deutlich spürbaren Druckpunkt" which loosely translates to "the clearly noticable pressure point".

History[edit | edit source]

The Siemens ST switch was manufactured by Siemens EC division for their own Transdata Terminal keyboards and teletypewriters in the 1970's and 1980's; the Siemens ST switch was not present in the catalogue of preferred parts (Schwerpunkttypen) that Siemens sold to others.

The Siemens ST switch was already used for the Transdata system a year before the Siemens T1000 was introduced. They are mostly associated with these teletypewriters, which were in widespread use and for which a lot of material can still be found on the web, whereas the elusive Transdata terminals had already disappeared in the 1980s.

The Siemens patent, DE2933983 / US4365903, filed in August 1979. The patent is about a modification of the switch, so it is not actual proof of the original switch:

"Luminous-indication key for key boards in office and teleprinting machines. A lockable key for use on electronic keyboards in office typewriters and teleprinters has a receptacle at an upper portion thereof for receiving a light emitting diode which is mounted in a small circuit board which can be snapped into the upper portion of the key and which is supplied current via flexible interlaced wires. A lower portion of the key has a guide element which cooperates with a guide pin carried on a side of the key base for retaining the upper portion of the key in a depressed state after a first actuation thereof, and for allowing return of the upperportion of the key to the original position after a successive actuation thereof."