CASSETTE_DRIVE_CONTROLLER

Published:2009/7/7 2:08:00 Author:May | From:SeekIC

Used in high-quality stereo cassette deck operating from AC line or battery. Combines current source for cassette-retaining solenoid with speed control for drive motor. As motor turns, associated motor-driven pulse-generating switch keeps Tr1, conducting; this cuts off Tr2 and allows current to flow through Tr3 for energizing solenoid. When motor stops, pulse-generating switch also stops and Tr1 stops con-ducting. After 3-s delay determined by C2 and R5, Tr2 conducts and solenoid is deenergized, releasing cassette. In speed control circuit, Tr5 acts as constant-current source for motor, using feedback from its collector to base of Tr4 Back EMF developed by motor is applied to emitter of Tr4 reducing its forward bias and reducing current In the base of Tr5, so as to stabilize motor Article gives all other circuits of cassette deck and describes operation in detail.-J. L. Linsley Hood, Low-Noise, Low-Cost Cassette Deck, Wireless World, Part 3-Aug.1976,ρ55-56(Part 1-May 1976,p 36－40, Part 2-June 1976.p62-66.)



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