VARIABLE－CAPACITANCE_DIODE_SPARKED_VCO

Published:2009/7/9 3:52:00 Author:May | From:SeekIC

You can transform a 741S124 multivibrator into a wideband VCO by replacing it conventional ftxed capacitor with a variable-capacitance diode. The only disadvantage of this scheme is the 30-V biasing volt-age that the diode requires. Capacitors C1 and C2 couple the Philips BB909A variable-capacitance diode to the 74S124. R1 and R2 are large enough to isolate ground and control voltages from the timing capacitors. Resistors R3 and R4 form a voltage divider for the 74S124's control input.



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