Crystal_controlled_square_wave_oscillator

Published:2009/7/25 3:17:00 Author:Jessie | From:SeekIC

In this circuit, the values of R1 and R2 are equal so that the LM139 comparator switches symmetrically about +Vcc/2. To ensure a 50% duty cycle, the RC time constant of R3 and C1 is set to be several times greater than the period of the oscillating frequency (which depends on the crystal resonant frequency).When specifying the crystal, order series-resonant, along with the desired temperature coefficient and load capacitances to be used.



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