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A metallic blue glitter box photographed face on. Grubworks is lettered across the top in sparkly silver, with vol beside a chrome knob at the top left. Below that is a row of four chrome knobs, two at the left and two at the right, with a small LED between them and ON lettered under the LED. Three toggles sit under the knobs, one over the word chew at the left, one under ON in the middle and one over the word hum at the right, and a row of seven toggles runs along the bottom edge.

Grub Divider + APC + Opto Duet · One of a kind

Grubworks

Synth Available · 1 of 1

Three of my circuits in one blue glitter box: my Grub Divider, an Atari Punk Console and my Opto Duet. The APC and the Opto Duet are on their own toggles, so you can run them together, one at a time, or not at all, and there is a line in for anything else. The Opto Duet turned out to have an actual tempo, so when the Grub spits its signal back out it makes a beat, like 3 up 1 down, and the box sounds rhythmic all by itself without any other signal.

  • TypeThree circuits in one box: a CD4024 seven-octave divider, an Atari Punk Console and a pair of 555 timers coupled by light
  • BoardsStripboard, including my own Grub Divider and Opto Duet layouts, both free guides
  • Controlsvol; two knobs and an on switch each for chew (the APC) and hum (the Opto Duet); seven octave toggles; ON, with a power LED
  • InputLine in on the top edge, into the divider
  • OutputLine out on the top edge. Only the divider reaches it; the APC and the Opto Duet are heard through the Grub
  • Enclosure1590BB, metallic blue glitter, silver lettering
  • Power9V DC, center negative
  • BuiltOctober 2026
  • StatusAvailable - one of a kind
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What it is

The Grub Divider is a CD4024 binary counter. Whatever you feed it comes back out an octave down, two octaves down, and so on to seven, and each of those octaves has its own toggle along the bottom of the box, so you build the sound by flipping them on. Everything in here goes through the Grub: the Atari Punk Console and the Opto Duet are its sources, and only the divider reaches the line out.

chew is the Atari Punk Console. hum is the Opto Duet: two 555 timers that only talk to each other through light, a slow one flashing an LED sealed against a photocell that sets the pitch of a fast one. In here its two knobs take the place of the photocells it usually has on the outside.

Controls

vol
The Grub divider's volume.
chew
The Atari Punk Console: two knobs, and the toggle above the word to switch it on and off.
hum
The Opto Duet: two knobs in place of its photocells, and the toggle above the word to switch it on and off.
The seven toggles
The divider's seven octaves, one per toggle. Any mix of them can be on at once.
ON
Power for the whole box. The LED above it is the power light.

The line in

The line in on the top edge goes into the divider, so anything with a signal can go through the Grub as well as, or instead of, the two voices inside. Turn chew and hum off and it is a seven-octave divider for whatever you plug in.

Demo

Demo video coming soon.

Or build the boards yourself

The Grub Divider and the Opto Duet are free stripboard guides on this site, each with the drawing, the parts list, the netlist and the file you can open in Copper Bottom. The Atari Punk Console has a free breadboard guide.