Quad Optical Trigger

I’ve been collaborating a lot lately with Erich Ragsdale, an experimental filmmaker, musician, gadget hound, and DJ. As part of his June 2008 art installation “Stereopticon” at Austin’s The Opera House, we performed together as Operation Playmate. Our concept was to do a show with new instruments based on light; for several weeks we prepared a set of experimental devices to debut at the performance. I desperately need to document this stuff in detail, but that will come in due time.

• Optigan disc reader
• circular optical sequencer
• tonewheel projectors
• sound cameras
• drum sequence projector
• strobe projector
• quad optical trigger

The Quad Optical Trigger, although built in a hurry, turned out to work well. It translates light levels and fluctuations into analog-synth compatible CV, trigger, and gate signals. Each of its four channels has a light sensor on a 15′ cable, with a magnet attached. The magnet makes it easy to clip the sensor onto a projection screen via a second magnet behind the screen. This allows sonification of visual imagery. Here’s a look at the four sensors:

Each channel has a switch to select the light-response polarity, i.e. bright light = high CV voltage, or bright light = low CV voltage; there is a knob to adjust the CV amplitude, and CV comes out on a 1/4″ jack. There is also a Gate/Trigger output jack with a switch to select gate/trigger mode, and a trigger threshold adjust knob.

Here’s a look inside the unit:

Presently, Erich and I are working on sequencing analog drum sounds using the Quad Optical Trigger via a 35mm film loop containing rhythm patterns scratched into the emulsion. Erich has a great shutterless film loop projector called the “Optokinetic Stimulator” that works nicely as a visual loop machine with forward/reverse and speed control.

Anyhow, despite some rough spots, the Operation Playmate show seemed to go over well with part of the audience… and I basically collapsed after it ended due to lack of sleep and food! Good times. The awesome Paul Baker shot a nice VHS video of part of the performance and I hope to get it online soon…