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Sold · found a home

A glossy white box photographed face on, GRUBWORKS hand-lettered across the top in green, with a chrome knob on its own at the top right. Below the name is a row of four chrome knobs, two at the left and two at the right, with a small LED between them. CHEW, ON and HUM are lettered across the middle, each over a toggle, and a row of seven toggles runs along the bottom edge.

Second build · Grub Divider + APC + Opto Duet · Glow in the dark · One of a kind

Grubworks

Synth

Three of my circuits in one glow-in-the-dark 1590BB: my updated Grub Divider, an Atari Punk Console and my Opto Duet, each one powered on its own. chew is the Atari Punk Console, hum is the Opto Duet, and the seven toggles along the bottom are the divider's octaves.

  • TypeThree circuits in one box: a CD4024 seven-octave divider, an Atari Punk Console and a pair of 555 timers coupled by light
  • Controlsvol at the top right; two knobs each for chew and hum; a toggle each for chew, ON and hum; seven octave toggles along the bottom; a green LED
  • CircuitMy updated Grub Divider, my Opto Duet and an Atari Punk Console, three boards, each powered on its own
  • Enclosure1590BB, glow in the dark, green lettering
  • Power9V DC, center-negative barrel jack
  • BuiltOctober 2026
  • StatusSold - found a home, October 2026
  • StatusAvailable - one of a kind
$180 Sold · found a home Ask about a similar build

What it does

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. chew is an Atari Punk Console. hum is my 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. Both layouts are free guides on this site.

Demo

Demo video coming soon.

Controls

vol
The knob on its own at the top right: the Grub divider's volume.
chew
The Atari Punk Console: two knobs, and the toggle under the word.
hum
The Opto Duet: two knobs, and the toggle under the word.
The seven toggles
The divider's seven octaves, one per toggle. Any mix of them can be on at once.

Circuit: my own Grub Divider layout, free on this site, with my Opto Duet and an Atari Punk Console. Built, painted, and finished by Onion Madder as an original one-off - not affiliated with, endorsed by, or a clone of any commercial brand.