500_5000_Hz_SQUARE_WAVE_DOUBLER

Published:2009/7/4 22:27:00 Author:May | From:SeekIC

Circuit shows virtually no deviation from 50% duty cycle over entire frequency range. Four NOR gates in CD4001AE IC form edge detector that presents negative pulse to 555 IC timer on both rising and falling edges of input square wave, to achieve frequency doubling. High-gain 741 opamp amplifies any difference between DC level at timer outputand reference equal to half of supply voltage, to send correction voltage to pin 5 of timer for forcing output to 50% duty cycle.-L. P. Kahhan, Frequency Doubler 0utputs Square Wave with 50% Duty Cycle, EDN Magazine, June 5, 1977, p 211-212.



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