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.
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.
555 Theremin on Stripboard: A Copper Bottom Layout
the first layout in the series, and proof of the whole idea: the 555 theremin soldered onto a 9×18 scrap of stripboard, drawn and checked in Copper Bottom and built exactly as drawn - it worked on the first power-up. Download the layout file, import it into the editor, and let its walkthrough, checks and build sheet carry you through the soldering.
Opto Duet: Two 555 Theremins That Play Each Other
two 555 theremins on one stripboard, coupled by nothing but light: a slow engine ticks, its bare LED flashes behind the output cap, a homemade vactrol carries each flash into the voice's timing chain, and the box chirps. With the verified layout file for Copper Bottom, the off-board wiring, and the story of why the LED only works on one strip. Built, boxed and demoed - about 45 minutes at the bench.
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.
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.
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.
Nothing In Here: Three Months Bending a VTech Super Sound Works
every capacitor, every resistor, the chips - and essentially nothing in the whole toy. What I probed, the two bends that did turn up and why neither was worth keeping, and the one modification that is: the crystal clock, which moves pitch, tempo and playback all at once.
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 Micro Sample & Hold
Ray's compact sample-and-hold with its own clock and a glide control, sized to add onto the Sound Lab Mini-Synth - schematic, PCB artwork, panel drawing, and his scope traces walking through the whole sampling process step by step.
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.