DUTY_CYCLE_CONTROL

Published:2009/7/1 20:17:00 Author:May | From:SeekIC

Feedback loop through two transistors automatically adjusts timing of MVBR to hold duty cycle constant over wide range of triggering rates. 2N3904 acts as integrator with time constant much longer than pulsing period. If duty cycle increases or decreases, current into integrator becomes positive or negative and DC voltage at its collector slowly decreases or increases. This collector voltage drives 2N3906 operating as current generator for adjusting automatically to give chosen duty cycle as selected by 1K pot. Range is 17% to above 50%.-J. L. Engle, Regulate Duty Cycle Automatically, EDN Magazine, Nov, 5, 1978, p 122.



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