Average value tachometer for a disc drive servo and the like

摘要: In a disc pack data storage system that has plurality of discs and heads for coaction with the discs, tachometer producing signal indicative radial speed respect to discs. At least one surfaces is servo surface at head so in response movement triangular position produced. Sampling pulses specific positions are derived from time required move between two represented by adjacent sampling inversely proportional speed. Control computing circuitry measures providing clock pulse source counting number occur pulses. There controlling employed accordance frequency controlled achieve accuracy all speeds. A digital analog converter converts counted voltage amplifier derives Circuitry active very low speeds serves combine integrating motor current an accurate produced