In article , Rich Grise wrote: [...]
Or use the flip-flop type phase detector not the XOR one. The 4046 has both types on it.
Or raise the VCO's frequency to 6X the input. like this:
Look here:
CD4046 pins used in this design:
Signal In = pin 14
This pin has some bias circuits hooked to it so you can apply a small signal through a capacitor. If your signal is already going from ground to Vcc, just ignore the bias stuff and hook it up.
Internally this signal goes to both phase detectors as the expected "input".
Phase Comparitor feedback in = pin 3
This pin hooks to the output of the divide by 3 (or 6) counter. This is expected to be the "feedback signal".
Phase comparitor 2 out = pin 13
This pin is driven high if the feedback signal is slower than the "input" signal. If the feedback is faster, it is driven low. If it is just right the chip floats the pin.
This normally hooks to an RC low pass filter.
VCO in = pin 9
The voltage on here controls the frequency the (V)oltage (C)ontrolled (O)scillator runs at. A high voltage means faster.
C1A and C1B = pins 6 and 7
You hook a capacitor of many pF between these pins to help set the frequency of the VCO. A bigger capacitor means slower.
R1 = pin 11
Pin needs a resistor to ground. This resistor sets the amount the frequency changes as the "VCO in" is taken fron ground to Vcc.
R2 = pin 12
This pin also gets a resistor to ground, or may be left open. This controls the frequency the VCO runs at when the "VCO in" is at ground. If it is open, the VCO usually just about stops for zero volts.
Page 9 tells you about R1, R2 and C1. Remember the VCO is running at twice (4 times) the output frequency.