The Deaf Watchmaker

Reconfigurable Mechanical Sequencer/Modular Synthesiser

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Using different sized gears with various sensors mounted on them, and small, simple sound synthesis modules, produce complex repetitive drone 'music' - think Basic Channel with a hand crank. Gears are mounted on a pegboard to allow 'composing'. This is something I've had in the back of my head for a couple of years now, somewhere between a woodworking, electronics and art project.

I had this idea after being up for 36 hours a few years ago, as a kind of meeting place between Braitenburg Vehicles, Analog Sequencers, the Atari Punk Console, and Lego. The basic concept is that parameters on an analog synth are controller by variable resistors usually, but those could be some other kind of resistor, like LDRs. An LDR in a short tube will have an "interesting" voltage profile as it passes by a light source. Putting the whole thing on a rotating platform adds 'rhythm', and different sized gears adds complexity/interest (if you are interested in droney electronic music, which I am).

Gears will be in the style of Mathias Wandel's gears, with a 4-pole TRRS plug pushfitted in the centre. The plug carries power to the gear, and also audio back from the gear. The plugboard is a grid of 4-pole sockets with a simple audio mixer in the back to produce the final audio output. Gears have a series of dowel holes around the edge to mount sensors or emitters, and a central mount for a small PCB. The PCB is powered by the TRRS power, and contains either a synth module (simple 555/logic gate stuff, most likely), and/or sockets to connect emitters and detectors to from the edge of the gear.

I'd like to find a stash of those old telephone exchange TRRS plugs (e.g. GPO plugs in the UK) if I can, rather than the wimpy TRRS plugs that mobile phones use. Clunky is better.


0 - Complex behaviour from simple rules.

1 - No magic. It should be very obvious from looking at it what is going on (apart from the actual synth circuits, I guess)

2 - Usable. It should be possible to produce a definite variety of sound - perhaps this will need a triggered sample player? I feel that is cheating though.

3 - Using other forces (magnetism, gravity) is definitely allowed. Also strobes for effect at a distance, or perhaps filters to select what is affected.

4 - Tactile. Hand cranked, clattery, chunky and pleasant to handle parts.

  • Old Jack City

    Howard Jones10/10/2015 at 10:59 0 comments

    This is GPO Plug 420 - the standard for UK telephones from the mid-60s to the 80s when the post office spun off the phone system to British Telecom and switched to a plastic IDC plug. It's about 1/4" across, so it's nice and chunky. The jacks are 60s-quality engineering too. Hopefully the gears can rotated fairly freely and the jack will maintain contact - the 4 pins will be ground, power, audio out, and possibly a separate audio ground, if it needs it. The back of the baseboard will be a point-to-point wiring mess, but basically a passive mixer for all the grid of jacks, feeding into an amplified output. By using the last ring for power, they will only power up when fully clicked home.

    I found a couple of surplus suppliers for these plugs at not-terrible prices yesterday. Considering there must have been millions in use at one point, they're surprisingly hard to find.

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esot.eric wrote 10/10/2015 at 10:39 point

I dig it. I had an idea like this a while back, where the gear-hubs are attached to magnets, for mounting on a fridge.

  Are you sure? yes | no

Howard Jones wrote 10/10/2015 at 10:45 point

Yeah, I figured that either you'd have to have each gear carry its own amplifier, speaker and power, or there would need to be some sort of baseboard to keep it simple and light. I found a couple of suppliers yesterday for these old school telephone connectors (I think they are also used in aerospace for pilot's headsets) - nice and chunky, and hopefully the wipers on the jack will stay in contact but still allow the gear to turn.

I had a couple of related ideas - hall-effect with magnets instead of led/ldr for the communication, and also possibly using the same gears to run a tape loop somehow (I love the sound of Roland Space Echo!). Also, some sort of pendulum/tilt sensor, so that a gear can trigger just based on its position, not relative to something else - the relationship between the periods of different sized gears is going to make for some long cycles, and I think it'd be useful to get something like drums or faster rhythmic sounds in there somehow.

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esot.eric wrote 10/10/2015 at 12:22 point
I'd considered sound on each gear, maybe something simple like those CMOS audio oscillator circuits they've been doing on the blog. Also thought there might be use for different types/sources of sounds on each gear... some might be circuitry-based, others might be physical, like your drums, maybe solenoids and bells, or something... Each gear could be its own "thing", developed as you go.

Those jacks look like a great idea, sliprings aren't cheap, and most aren't removable.

Anyways, easily-changed and easily-viewed/understood mechanical sequencer. Excellent :)

Tape-loop, awesome. I'd thought about chains/sprockets, or even pulleys and belts, as another means of transferring locomotion. I kinda gave up on those with my magnet-mounts since tensioning would be difficult. But in your setup tape-loops could *be* the belts. Very cool. Even just short samples of audio from old cassettes. And... Echo... Nice.

It'll be fun to watch this one progress.

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