CD4046 VCO · One of a kind
Dragonfly
A CD4046 phase-locked loop used as an oscillator, on my own Dragonfly VCO stripboard layout, boxed upright in lilac. Pitch, range and volume, plus a power starve knob, a mode toggle, and a bend of mine on a third toggle that drops the whole thing about an octave. The LED is a bend too: it flickers with the pitch knob and pulls the whine off the top.
- TypeCD4046 phase-locked-loop VCO, on stripboard
- BoardMy own layout, the free Dragonfly VCO guide
- ControlsFour knobs: pitch, range, volume, starve. Three toggles: mode, power, drop. One UV LED
- Output3.5 mm jack on the face, bottom left. The CV and line inputs on the guide's layout are not fitted on this one; it is an oscillator, not a processor
- Enclosure125B, stood upright, lilac, the name in pastel lettering down the side
- Power9V DC, barrel jack on the face, bottom right
- BuiltSeptember 2026
- StatusOne of a kind. When it is gone it is gone
What it is
The CD4046 is a phase-locked loop chip, and one of the things inside it is a voltage-controlled oscillator that the rest of the chip is supposed to steer. This build uses that oscillator on its own terms. Pitch is a control voltage into it, range sets how far the pitch knob can reach, volume is volume, and mode changes what the chip is doing with its own loop.
The starve knob is a 100K pot in the supply. Turn it up and the chip runs short of volts and gets strange before it gets quiet. The drop toggle is wired between the range pot's bare lug and the chip's supply pin, and throwing it drops the tone about an octave. The LED sits across two strips of the board with no resistor; it flickers with the pitch knob and takes the high whine off. Neither bend is in the guide's layout file. They are prose on the guide page and copper in this box.
The controls
Pitch, range, volume and starve are the four black knobs, two rows of two. Mode, power and drop are the three toggles in a row under them. The LED at the top is ultraviolet, so it reads pale violet to the eye and blue-white to a camera.
The box
A 125B stood on end, lilac, everything on the face: output bottom left, power bottom right, the name in pastel lettering down the side. The same upright format as the Devil's Triangle, so the two stand together.
Demo
Demo video coming soon - it's on the bench being filmed.
Or build it yourself
The layout, the parts list and the netlist are the free Dragonfly VCO guide, with the file you can open in Copper Bottom. The guide also has the drill template for this exact box, and describes both bends in words, since neither is drawn.