Onion Madder's Tutorials
DIY electronics, built to be readable on any device.
A collection of electronics tutorials, from beginner to intermediate - maybe someday advanced.
Paper Circuits
Circuit boards you print. The drawing is the board, the holes are poked with tweezers, and the traces are bare wire laid along the lines on the back. I love the concept of Peter Blasser's paper circuits, but his are complicated, use esoteric parts and are difficult to troubleshoot - so this series takes circuits you already know, with common parts, and makes paper circuits something a beginner can try.
Paper Mosquito: The Atari Punk Console on a Printed Sheet
the Dead-Bug Mosquito's NE556 APC rebuilt as a paper circuit: print the fold sheet, glue it around a folded core of plain paper, poke the holes and lay bare wire along the lines. One chip, ten parts, the chip soldered straight to the paper. Fifty-nine steps from the middle outward, a printable build sheet, a voltage check and a troubleshooting table.
Paper Opto Duet: Two 555s That Talk With Light
the Opto Duet as a heart-shaped paper circuit: one 555 ticks, every tick flashes an LED into a photocell in the other 555's timing, and it chirps on the beat. A tempo eye and a pitch eye stand up on the board, the vactrol is an LED and a cell in black heatshrink, and the battery snaps on. Same circuit and values as the stripboard one, and this one is built too. Sixty-four steps and a printable build sheet.
See all 10 paper circuits » 8 more
Stripboard Layouts
For when a circuit has earned a permanent home but not a printed board: veroboard and stripboard layouts for the builds in the other series, with the cuts and links marked out. These are drawn and checked in Copper Bottom, the stripboard editor in the top nav - each layout file downloads from its guide and opens straight into it.
Rungler
A small Rungler after Rob Hordijk: one 40106 oscillator clocks a CD4094 shift register and the other feeds it bits through an XOR, the register's last three bits become a stepped voltage, and that voltage bends the pitch of both oscillators, so the pattern rewrites itself. Two pitch knobs, two depth knobs, a toggle that locks the eight bits into a loop, and the two oscillators ring-modulated into the mix. With the layout file for Copper Bottom, the netlist and a 125B drill template.
Opto Wobble
The Opto Duet and the Dual-Wave LFO on one board. The LFO goes through an on-off-on toggle straight into pin 5 of either 555, so it wobbles the engine's tempo or the voice's pitch, a CV jack goes into the engine's pin 5 through 47K, and a 2K pot in the supply starves the whole board. Built as drawn. With the layout file for Copper Bottom, the netlist and a 125B drill template.
See all 46 stripboard layouts » 44 more
Eurorack Modules
The bug boards from the stripboard shelf as 3U rack modules: each one the built board hole for hole plus a rack block - power header, a diode per rail, a 78L05 and a TL072 - with a 1:1 panel drill template. Drawn and checked in Copper Bottom; most of the modules are not built yet, and every page says so, but the Output Rack and the battery bench supply that tests them are.
Battery Breakout
A bench supply for bringing a module up before there is a case. Two 9V batteries in series make ±9 V into the same 2×5 power header the modules take: nothing to plug in backwards at the wall, not much current into a short, and every module here already has a diode on each rail. An LED on each rail says its battery is in the right way around, and one toggle switches both rails together. With the layout file and the netlist.
Output Rack
The way out of the rack. A rack signal swings about 10 V peak to peak, which slams a pedal and clips most line inputs, so this brings it down to about a fifth through a divider, buffers it with a TL072 on each side of a log volume pot, and sends it out of a 3.5 mm jack through a cap that blocks any DC. Mono, one knob, 6 HP. With the layout file, the netlist and the panel drill template.
See all 13 Eurorack boards » 11 more
The Breadboard Series
The no-commitment way in. Each of these goes together on a solderless breadboard - push the parts into the holes, follow the rows, and you're making noise in about twenty minutes - or forty for the six-voice Hive, which is the big one. Same circuit family as the Dead-Bug Series below, so when a build earns a permanent home, the soldered version is waiting. Never touched a breadboard? Start with the 555 Optical Theremin - the only one here with a speaker wired straight in, so it makes a noise on its own without an amp, and the only one you can actually silence.
555 Optical Theremin: Two Photocells on a 555 Astable
one 555, two photocells and a speaker. The cells sit in series as the timing resistor, so either hand moves the pitch and both together move it further - and cupping both stops the note dead instead of letting it sag, which is what makes it playable. Sixteen steps, no soldering at all, and it drives the speaker directly with no amp. Hole-by-hole recipe, pinout card, troubleshooting table and a power-LED mod.
Breadboard Hive: A Six-Oscillator CD40106 Drone Box on a Breadboard
the whole six-voice Hive with nothing soldered but the pots, so swapping a range cap takes two seconds instead of two minutes. Row-by-row recipe for all forty-five steps, grouped by part like the rest of the series, and the full troubleshooting table. The longest build in this series at about forty minutes.
The Dead-Bug Series
One chip, no circuit board. Each of these is a noise-maker built dead-bug - the chip flipped legs-out and every part soldered straight to them, no breadboard, no PCB. They share a power source, they share a method, and they're built to feed each other into one bigger instrument. New to it? Start with the Mosquito, then the Hive.
Dead-Bug Mosquito: A Point-to-Point NE556 Noise Box
build the classic NE556 stepped-tone generator with no breadboard and no PCB - dead-bug, soldered straight to the chip's legs. Full parts list, pinout, a pin-by-pin netlist, and how to add CV inputs and a line / clock output.
Dead-Bug Hive: A Six-Oscillator CD40106 Drone Box
turn a CD40106 hex inverter into six square-wave oscillators in one chip - a whole hive of detuned drones, dead-bug and point-to-point. Parts, pinout, a pin-by-pin netlist, a resistor mixer, and how to cross-modulate the voices.
Circuit Bending
Taking something that already makes a noise and making it make the wrong one. Module mods, teardowns and the bends worth keeping.
Four Modes, One Chip: The ISD1820 Breakout Nobody Finishes Wiring
record, one-shot sample, loop - plus the feed-through megaphone mode almost every ISD1820 tutorial skips. Pinout, a mode state table, the desolder trick that makes parts fall out, and the loop jumper that isn't on any schematic for this board.
The Groaner
Pointless Electronics PE-002: pick it up and it groans, like an old-school groan tube. An ISD1820 with a groan recorded into it and its pitch resistor swapped for 470K so it plays back slow and deep, a tilt switch across the play button, a speaker hot-glued behind a grille in the front, straight off the module. Four solder joints, a grille template, and the one-shot board that turned out not to be needed.
Power
The two guides everything else runs on: how cells behave in series and in parallel, and how to build a rechargeable pack out of salvaged vape batteries. Worth reading before you wire a supply to anything you care about.
More Volts or More Hours? Batteries in Series & Parallel
series adds volts, parallel adds hours - with diagrams for both, plus series-parallel, the matching rules nobody mentions, how to run 9V and 6V off one pack, and using a multimeter to find out which wire is which.
Rechargeable Battery Pack from Two Dead Vapes
salvage the lithium cells out of two used disposable vapes and wire them into a rechargeable battery pack for your builds.
Mirrored Guides
Favorites from around the web, preserved here so they don't vanish. Every one is credited to its original author, and I only touch the code, not the content - a card marked Mirror means the words and photos belong entirely to the person who made it, and the link in the card takes you to them. The same promise covers the MFOS shelf below. If you're the author of a mirrored guide and want it removed, just email me.
Modifying a PT2399 Delay Board to Break Out the Controls
Turn a cheap, ubiquitous PT2399 delay module into a proper knob-controlled delay - delay time, feedback and mix broken out, step by step, with photos of every joint.
Modifying an ISD1820 Voice Recorder Board to Be a Lo-Fi Sampler
Turn a cheap ISD1820 voice-recorder board into a lo-fi sampler with pitch control - swapping the mic and speaker for 1/4" jacks, breaking out record and play buttons, and replacing R4 with a pot to sweep the sampling frequency.
Modifying the Radica UCreate Music into a Real-Time Multi-FX
A deep teardown-and-mod of Radica's short-lived UCreate Music toy - breaking out the Big Button to DB9 sockets, adding pots, a volume-pedal jack and a 'Hold' footswitch to turn it into a playable multi-effects unit.
MFOS Legacy Projects
Music From Outer Space was Ray Wilson's life's work - the project that started countless people on synth-DIY. Ray passed in 2016; these pages keep his beloved designs accessible and in his own voice. Why I'm building this »
MFOS 16 Step Sequencer
Ray's two-board analog sequencer: 4 to 16 steps, reverse, reset, stop and random modes, and coarse, fine and a gate switch on every step. All four schematic pages, both boards, the panel wiring and the panel overlays, drawn sharp from his PDFs.
MFOS Weird Sound Generator
Ray Wilson's classic first-synth project, preserved - the full build, schematics, panel and case drawings, plus his troubleshooting guide and modifications. A little museum for a beloved MFOS design.