CD4093 drone synth · One of a kind
Garden Variety
A CD4093 quad NAND drone synth on my own stripboard layout, in a tin covered in pansies, with far more bends on it than it has any business having. Six knobs and six toggles. One toggle is the power switch and one knob is the volume, because it has its own amplifier and speaker in the tin now. Everything else is a bend, and I am not going to give you a knob list, because it does not have one.
- TypeCD4093 quad NAND drone synth, my own design
- BoardStripboard, from my own Cicada NAND layout - the fourth one I have built
- ControlsSix knobs, six toggles. One toggle is power, one knob is volume; the rest interact
- OutputBuilt-in LM386 amplifier and speaker with a volume knob, plus a 3.5 mm line out that mutes the speaker when a lead is in
- EnclosureDecorative floral tin - the lid is the panel
- Power9V battery, inside
- StatusOne of a kind. When it is gone it is gone
What it is
A CD4093 is four NAND gates with Schmitt trigger inputs, which means each one will happily oscillate on its own with a resistor and a capacitor hung off it. Gate them against each other and you get drones that pulse, stutter, tear and beat, which is the whole point of the chip and why it turns up in so much noise gear.
The board in here is my own Cicada NAND layout, which I drew, published as a free guide, and have now built four times. This is the fourth, and it is the one I kept adding to.
Why there is no knob list
There are twelve controls on the lid. One toggle turns it on and one knob is the volume. The other five toggles and five knobs are bends I put in on top of my own circuit, and here is the honest situation: most of them only do anything depending on where the others are sitting. A knob that is dead in one configuration is the most important control on the box in another.
So I cannot hand you a legend, and I am not going to invent one. That is not a fault, it is what the instrument is. You find combinations, and the combinations are the instrument rather than the individual controls. If you want a synth where each knob does one nameable job, this is emphatically not it.
The red lamp on the lid tells you it is on, and the knob marked VOL is the volume. Those two I can explain.
The tin
A decorative tin printed all over with pansies, with the lid as the panel. Brass knobs and brass toggles, because on that pattern anything black looked like a mistake. It is a better looking object than most things that make this kind of noise, which was deliberate.
It runs from a 9V battery inside, and it now has an LM386 amplifier and a speaker in the tin with it, so it makes a noise on its own with nothing plugged in. The speaker is glued into the base and fires out through a cluster of holes drilled in the bottom, so it wants to sit on something rather than be held flat against a table. The knob marked VOL is the volume for that. The 3.5 mm line out, the standard headphone size, is a switched jack: plug a lead in and the speaker goes quiet and the signal goes down the cable instead, to an interface, a pedal chain or an amp with a 3.5 mm to quarter-inch lead. The LM386 is the same chip as the Dead-Bug Hornet, if you want to build one.
Demo
A short one, filmed by Onion Madder on the actual unit, through its own speaker.
Or build the board yourself
The layout inside this is free. The Cicada NAND guide has the stripboard drawing, the parts list, the netlist and the file you can open in Copper Bottom to check or change it before you cut a single strip.
What it will not give you is this one's bends, because I could not write them down if I tried. Build the board, then start bridging things and find your own.