SINGLE_CONTROL_FOUR_DECADE_VARIABLE_OSCILLATOR

Published:2009/7/5 22:52:00 Author:May | From:SeekIC

The circuit consists of a variable current Source that charges a capacitor, which is rapidly discharged by a Schmitt-trigger comparator, The sawtooth waveform thusproduced is fed to another comparator, one with a variable switching level. The outputfrom the second comparator is a pulse train with an independently adjustable frequencyand duty cycle. The variable-frequency ramp generator consists of capacitor C1, which is charged by a variable and nonlinear current source. The latter compnses a 2N2907A pnp transistor, plus resistor R1 and the potentiometer R2 Capacitor C2 eliminates any ripple or nolse at the base ofthe transistor that might cause frequency jitter at the output



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