Erosion Threshold

The Lumiphone

I’m at the refining stages of a design for a light sensitive classic analog synthesizer that can be played with hand shadows. It may also be the world’s most inexpensive and easy to build analog synthesizer, as it does not contain any specialized components or special calibration circuitry. The result is a fun to play musical instrument with lots of timbral possibilities – pretty much identical to a Moog style synthesizer. The synthesizer, which I will call here a “Lumiphone,” bears its parameters to the player for instant connection, unobstructed by buttons and wheels or programming. It’s all raw at your fingertips, like a violin. This enables the player to make more expressive music, compared to that produced by your average keyboard synthesizer. It’s also a lot more work to play. You can’t just push a few buttons and hit play to get an acid baseline like the famous Roland TB-303. For this reason, even though structurally they are equivalent synthesizer designs, the lumiphone sounds different from the TB-303 and the like. I think the lumiphone will be most adored for its vast timbral pallet – which are all accessible at the flick of a wrist. It will of course also be adored for its accessibility in price and ease of construction.

Forgo tonality, gain simplicity and affordability

I found that the greatest barrier to entry in making a home brew synthesizer was the expensive and rare parts. It turns out that those special parts aren’t essential to the actual sound producing circuitry. I had to do a lot of research to figure out how to redesign the circuits without temperature and linearity compensation. The key was eliminating the voltage control paradigm and replacing it with light as the common control signal. In turn, the circuits reduce to a simple set of designs that any beginner hobbyist could put together in an afternoon. The trade off is of course that the pitch of the synthesizer may vary slightly given changes in temperature. This is irrelevant if you play the circuit by ear, rather than with a keyboard with fixed notes. It is also irrelevant to noise artists and experimental musicians who actively step away from tonality.

Light control

Light turns out to be a convenient and interesting control signal. You can play the lumiphone with hand shadows. You can also play it with a microcontroller like an Arduino by varying the brightness of an LED. You can even play the lumiphone with the brightness of a computer screen – which can be controlled by a custom program written, for example, in Pure Data or even Javascript. CDS cells take the light cast on them to produce a resistance. This variable resistance is used in the synthesizer to control different things, namely the Frequency of the Oscillator, and Cutoff of the Filter.

Onword!

Given the surprising versatility of this lumiphone, paired with it’s thrifty and accessible design I think this thing could be the beginning of something great. I hope it will be a useful design also for noise artists, circuit benders, and electronic musicians who will no doubt want to adapt it and borrow different elements to repurpose them for their own designs – like the Atari Punk Console. It also could be the beginning of a different kind of electronic music – a fresh start for the theremen. There’s still a lot of minor details to work out – like power supply design and deciding on the most accessible parts to call for – but soon I will be preparing some schematics and documentation for the project so that anyone with basic electronics skills can build one at home or in a classroom. In the mean time, if you click around on my blog enough you’ll be able to piece together most of what you need to build one.

Whittled Down Caravan in Popular Science Magazine

The canvas covered caravan my partner and I built as an experiment in affordable portable housing was recently featured in Popular Science Magazine. They did a really nice job documenting and photographing the project. We made the design ourselves and used a lot of salvaged materials. You can check out the article here:

You Built What?!: A Home for the Long Haul

and watch the video!

A Couple’s DIY Covered Wagon

Early December

Between The Forest and Frozen Lake to La Belle Dam Sans Merci

One of my photographs was featured in a music video for the up and coming electric classical guitar group Duo Orfeo. The super high resolution panorama was stitched together from several shots taken with a long focal length lens. I assembled the blizzardous scene using Hugin – an open source project worth checking out.

I discovered that due to the limited size and resolution of computer screens a “Ken Burns” view of the image is actually an ideal medium for appreciating these large images. I hope one day to have the resources to print this and several other composites I’ve been working on, but in the mean time this might be the best way to share these projects.

Cigar Box Ukulele

This is a ukulele I made out of a cigar box. I used friction peg tuners for an extra thrifty project. They are often called for in depression era cigar box ukulele plans so I thought I’d give them a shot. They are a bit challenging to use though, I will admit. I also chose to install only the first six frets, since anything past there seems silly on such a small instrument. I think if I made another one I’d put on one more fret, so you can get a 5th from the nut, but no more. It’s loads of fun to play, especially in the car, which you cannot do with a guitar. Here’s a video of it in action, with a low G string, which makes it play more like a guitar.

In a Landscape

In a Landscape, originally uploaded by Tristan Chambers.

Camera Obscura

I made a camera obscura as a gift this holiday season. While I was researching the principles behind the contraption I was drawn in by its simplicity and peculiar hybrid relationship with photography and fine art. Think of it as a camera, but instead of film or a digital sensor recording the image, you the artist with your pencil record it on a piece of trace-paper. I’m tempted to put it under the heading of “alternative photographic processes”, especially with all the recent interest in nonlinear tone mapping algorithms in photography, some of which are even based on brain neurology and old painting techniques. It’s also a good use for that weird beautifully patinad box you found at a junk sale.

 

Vodka Box Fiddle Demo

As promised, here’s a video of my home made fiddle in action played by a fellow musician at a party.

You can read more about it in my post Vodka Box Fiddle.

555 LCO & JavaScript Get Freaky Now

Perhaps the cheapest and easiest baseline synthesizer ever – made from a light controlled oscillator driven by the brightness of a laptop screen. A sequencer written in JavaScript varies the brightness of the patch, controlling the pitch of the synthesizer. Though it’s not included here the light controlled resonant filter I built in previous post could be added to this circuit – for next time! At a decimal fraction of the cost of a x0xb0x or TB-303, this open source hack could put transistorized bassline goodness in the hands of anyone with a hand-full of Radioshack parts.

The script varies the brightness of a patch on the computer screen, stepping through the values of the sliders. The sequencer has eight steps, and a tempo control. The patch of the screen is pointing at the CDS cell (light controlled resistor) which is shrouded by a piece of black heat-shrink tubing. You can play with a copy of the sequencer code here http://tristandabbles.com/SliderTraverse.html. WARNING at present it only works on Chrome and other web-kit browsers. Full screen (F11) to see the light patches. It’s JavaScript so you can hack as you please. I’ve done a bit to spruce it up. I added a second light patch to control a filter. It pulses with a simple decaying envelope every beat, which gives it that classic TB-303 sound. There are other features one could add to the sequencer, like buttons for accent or tying notes, LFOs etc.

I built the saw-tooth oscillator out of a 555. It can be done, contrary to what I said in a previous post. The trick is to supply a regulated current to the timing capacitor, which creates a linear ramp. This is done simply with a single transistor configured as a current source. Unfortunately you also have to isolate the output with a high impedance buffer. For the experiment I used a little Radioshack amplified speaker, shown in the video, which seems to have a very high input impedance as it didn’t effect the frequency of the oscillator at all. For a stand alone design an op-amp buffer stage would be required. So it’s a toss up as to whether this design is any simpler than the one I posted earlier which uses two op amps and a JFET.