Dead-Bug Grub
A CD4024 sub-octave divider & pattern box, point-to-point · By Onion Madder · Mess O' Pedals
This is the chip that gives the other two a bottom end and a pulse. The CD4024 is a 7-stage binary counter: feed it a tone and it hands you that same note one, two, three — up to seven octaves lower, all at once. Feed it a slow clock instead and those same outputs become a rhythm. It makes no sound on its own — it's the glue that turns your oscillators into an instrument.
Build four in the dead-bug series, after the Dead-Bug Mosquito, the CD40106 drone box, and the CD4046 VCO. This one plugs into any of them.
What a counter does, in one breath
Every time the clock ticks, a binary counter adds one. The clever part for us: each output stage toggles at exactly half the rate of the one before it. So if you clock it with a musical tone, Q1 comes out one octave down (÷2), Q2 two octaves down (÷4), Q3 three (÷8), all the way to Q7 seven octaves down (÷128). Exact halving means perfect octaves — tap one for a clean sub-oscillator, or mix several for a fat organ stack. Clock it slowly instead, below hearing, and those same outputs are gates ticking at ÷2, ÷4, ÷8 — instant rhythm.
⚠ Before you start tap to expand / collapse
Hot iron, obviously. 350°C of don't-grab-that. Ventilate, don't breathe the flux smoke, park it in its stand every time.
CMOS rule, one more time: no floating inputs. This chip has only two — RESET (pin 2) must go to ground, and CLOCK (pin 1) must be driven by an oscillator. A floating reset makes it freeze or glitch at random.
Mind polarity on the electrolytic output cap and your power source.
If you power it from a salvaged lithium pack, the usual cell cautions apply — see Do You Want to Survive the Vapocalypse?
What you'll need
New to the parts? Each line notes how to spot it — the printed marking, the package, or the polarity clue.
- 1× CD4024 (CD4024B / HEF4024) 7-stage ripple counter, 14-pin DIP — spot it: CD4024 printed on top, notch marks pin 1
- A clock source — this build needs a square-wave input. Your CD4046 VCO or a CD40106 voice is perfect; a 555 works too
- 1× 0.1 µF ceramic — supply decoupling (a non-polar disc printed 104)
- Mixing resistors — a handful of 10K for a grungy stack, or a binary-weighted set (10K / 22K / 47K / 100K / 220K / 470K / 1M) for a cleaner sawtooth (Step 5). Spot it: read the color bands or meter each one; non-polar
- 1× volume pot (10K–100K, B = linear taper)
- 1× 10 µF electrolytic — output DC-blocker. Spot it: a little can; the stripe marks the minus leg, longer leg is +
- Optional: a rotary switch or toggles to select which Q outputs you tap
- 1× SPST toggle for on/off — a 2-lug switch
- Output: a jack to an amp, or an LM386 (8-pin DIP) + speaker
- A power source — at least two vape cells in series (7.4V; three gives you 11.1V), or a 9V battery
- Solid-core hookup wire, enclosure, soldering iron, cutters, multimeter
Quick reference — the whole build on one card
Pinout plus every connection at a glance. The steps below go slowly; this is the bench card.
CP = clock in, MR = reset, Q1–Q7 = the divided outputs. Notch marks pin 1. Dead-bug (legs up) mirrors the map left-to-right.
Power & run
- Pin 14 → V+ (3–15V)
- Pin 7 → ground
- 0.1 µF across pin 14 ↔ pin 7
- Pin 2 (RESET) → ground
Clock in
- Pin 1 ← oscillator square wave
- CD4046 pin 4, or a 40106 output
- Counts on the falling edge
The outputs (octaves down)
- Q1 pin 12 = ÷2 (1 oct)
- Q2 pin 11 = ÷4 · Q3 pin 9 = ÷8
- Q4 pin 6 = ÷16 · Q5 pin 5 = ÷32
- Q6 pin 4 = ÷64 · Q7 pin 3 = ÷128
Mix → out
- Tap any Q → 10K → mix bus
- Mix bus → volume → 10µF → amp / jack
- One Q = clean sub-octave; several = stack
Step 1 Pin the bug down
Back to a 14-pin chip after the 4046's sixteen. Flip the CD4024 belly-up, glue its back down, and let the legs be your tie points. Count from the notch.
Step 2 Power rails — and ground the reset
Run V+ and ground, hook up the power pins, decouple at the chip. Then the gotcha for this one: RESET (pin 2) is active-high and must be tied to ground. Leave it floating and the counter freezes, resets randomly, or just sulks. Grounded = free to count. (Later you can bring a wire to pin 2 on purpose — that's the rhythm trick in “Going further.”)
| Connect | To | Why |
|---|---|---|
| Pin 14 | V+ | Supply positive (VDD) |
| Pin 7 | Ground | Supply negative (VSS) |
| 0.1 µF | Pin 14 → Pin 7 | Decoupling, right at the chip |
| Pin 2 | Ground | Reset held low = counter runs. Floating = glitch |
Pins 8, 10, and 13 are no-connects — leave them open.
Step 3 Feed it a clock
The 4024 is deaf until you give it something to count. Pin 1 (CP) takes a square-wave input and advances the counter on each falling edge. The other chips in this series put out exactly the clean 0V-to-V+ square it wants:
| From | To | Result |
|---|---|---|
| CD4046 pin 4 (VCO OUT) | Pin 1 | Octaves that track your pitch knob — the money patch |
| CD40106 voice output | Pin 1 | Octaves below a hand-tuned drone |
| Any 0–V+ square (555, etc.) | Pin 1 | Whatever you've got that ticks |
Share grounds. If the clock comes from another box, tie its ground to this one's or the counter won't see clean edges.
Step 4 Tap your sub-octaves
Now the payoff. Every Q output is your clock, divided down — a clean square wave one or more octaves below. Tap a single one for a pure sub-oscillator, or grab a few. Here's the whole map:
| Output | Pin | Divides by | Below the input |
|---|---|---|---|
| Q1 | 12 | ÷2 | 1 octave |
| Q2 | 11 | ÷4 | 2 octaves |
| Q3 | 9 | ÷8 | 3 octaves |
| Q4 | 6 | ÷16 | 4 octaves |
| Q5 | 5 | ÷32 | 5 octaves |
| Q6 | 4 | ÷64 | 6 octaves |
| Q7 | 3 | ÷128 | 7 octaves |
Wire a few Q pins to a rotary switch or a row of toggles and you've got a switchable octave selector. If your clock is an audible tone, Q1–Q3 are the musical sweet spot; if it's a slow clock, the same pins are your rhythm divisions.
Step 5 Mix them — stack or staircase
How you combine the outputs decides the sound. Give each tapped Q its own resistor into a shared mix bus, then run the bus to the volume pot. Two flavors:
| Goal | How | Sound |
|---|---|---|
| Octave stack | Each Q → equal 10K → mix bus | Fat, buzzy organ — the octaves piled up rough |
| Sawtooth / “melody” | Binary-weight it: Q7→10K, Q6→22K, Q5→47K, Q4→100K, Q3→220K, Q2→470K, Q1→1M | A stepped ramp — a gritty descending sawtooth, the classic counter-DAC tone |
Why the weighting: the slowest output (Q7) should count for the most, so it gets the smallest resistor. Exact values don't matter for a noise box — the wonky E12 approximations above just add character. Swap in a couple of pots to morph the staircase live.
Step 6 Take the output
Standard exit: block the DC, through the volume pot, out to an amp or jack. Same CMOS-output caveat as the last two builds — it won't drive a speaker on its own, so hand it to an LM386 or a real amp.
| Connect | To | Part |
|---|---|---|
| Mix bus | Volume pot (top) | — |
| Volume wiper | 10 µF → 1K → jack / LM386 in | + toward the pot; sleeve to ground |
Step 7 Power up
Feed it a clock, toggle on, and sweep the source oscillator. Every octave tap tracks the input in lockstep — move the 4046's pitch knob and the whole stack slides with it. Try clocking it slow enough to hear the outputs as separate ticks; that's your rhythm mode.
Voltage note tap to expand / collapse
CMOS again: 3V to 15V. At least two vape cells in series (7.4V — three gives you 11.1V) or a 9V battery.
One thing to keep straight — the 4024 is a divider, not an oscillator, so it has no pitch of its own. Its octaves are only as clean and in-tune as the clock you feed it. Run it from the same supply as its clock source and share grounds.
Step 8 If it won't divide
- Nothing on any output? Check pin 2 is at ground. A floating reset is the number-one 4024 problem — it holds the counter cleared.
- Still nothing? Is a clock actually reaching pin 1? Probe the source at pin 1 — no clock in, no counting out. Confirm shared ground with the clock source.
- Outputs on the wrong pins? Easy to mis-map — Q1 and Q2 are on the right side (pins 12, 11) while Q4–Q7 are on the left (pins 6–3). Double-check against the table.
- Weird stuttering / it resets on its own? Noise on the reset line, or you've accidentally tied a Q back to pin 2. Fine if intentional (see below); otherwise clean it up.
- Thin, buzzy octave stack? That's square waves piling up — expected. The binary-weighted mix (Step 5) smooths it toward a sawtooth.
Going further: rhythms, resets & the full patch
- Odd divisions via reset. Tie a Q output back to RESET (pin 2) and the counter clears early, before it reaches 128 — giving you division ratios that aren't powers of two, and lurching, looping rhythmic patterns. Put a switch or a few selectable Q taps on that reset line and you've got a crude pattern sequencer.
- Rhythm machine. Clock it from a slow 40106 voice (big cap, sub-audio) and the Q outputs become gates at ÷2, ÷4, ÷8… — use them to trigger the APC's one-shot or gate other voices for instant polyrhythm.
- Bit-mangling. Combine Q outputs through diodes or logic (a spare 40106 inverter) instead of a plain resistor mix, and the staircase turns into gnarlier, more melodic repeating figures. This is bytebeat territory — pure experiment.
- The whole trio, patched. 40106 LFO → 4046 CV in (movement) → 4046 square → 4024 clock (octaves + pattern) → mixer → amp. Three chips, one instrument — exactly what we set out to build.
That's the trio done. Clock this one from the dragonfly, pick your octaves, and you've got bass, movement, and rhythm out of three dollar chips and no circuit board. Show me what you make.
Binary counters as octave dividers and staircase oscillators are long-standing folk knowledge of the DIY-synth and Lunetta world. This write-up, wiring, and words are my own. Build it, bend it, make it yours.