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Scophony Type 123 High Speed Scanner

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Manufacturer Scophony
Model 123
Age 1938
Service Data No
Condition Fair, the motor and mirror are good, but the cable has perished.
Dimensions About 6" (150mm) high.
Comments This is a line scanning motor and mirror from a 1938 Scophony mechanicaly scanned projection television set. In the early days of TV, cathode ray tubes (CRTs) were mainly small and dim, only suitable for viewing in low light levels. To get a large bright picture, Scophony developed a projection system using a high intensity mercury vapour lamp. The light was modulated by a Jefferies cell, and then scanned across the screen by two mirror drums, a small high speed one such as this to produce the line scan, and a large slow speed unit to produce the frame scan (12 mirrors rotating at 250rpm). The type 123 consists of two motors running on the same shaft, a standard induction motor to bring the unit up to speed, and a Phonic motor (in reality another synchronous motor, but designed to work with High frequencies) which was synchronised to the Line pulses of the incoming signal the motors turned a mirror drum with 20 segments (visible at the top of the unit) at 30375rpm to produce the 405 line picture. For more details of the system see Scophony Systems and TVHistory.tv

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Copyright J.Beacon & M.Wroe-Parker 2003