Variable-capacitance-diode-sparked-vco


Posted on Apr 7, 2012

You can transform a 7415124 multivibrator into a wideband VCO by replacing it conventional fixed capacitor with a variable-capacitance diode. The only disadvantage of this scheme is the 30-V biasing voltage that the diode requires. Capacitors C1 and C2 couple the Philips BB909A variable-capacitance diode to the 745124.


Variable-capacitance-diode-sparked-vco
Click here to download the full size of the above Circuit.

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 745124"s control input.




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