Machine shops are dirty places with dust, metal particles, and oil in the air, the type of environment that plays havoc with precision instruments. To make sure their feedback encoder would be immune to shop-floor dirt and debris, engineers at Newall Electronics, Columbus, Ohio, designed their Spherosyn digital linear encoder so that none of the mechanical or electrical components are exposed.

The scale, for example, consists of a stainless-steel tube filled with individually-graded steel bearings. The bearings are preloaded at the factory, and the tube is then completely sealed. The read head containing the digital signal processor and associated circuitry is also sealed.

The encoder is available with TTL output and resolutions of 1, 2, 5, and 10 mm. Analog outputs of 1 Vpp or 11 mApp are also available. The encoder can output count rates as high as two million pulses/sec, letting it move at up to 20 m/sec. The Spherosyn Digital was deigned to provide feedback for all types of CNC, automation, and motion-control systems.