The performances based on the rhythm apparatus for the overhead projector, a robotic, audio-visual instrument I presented and demonstrated at Nime 2014. I combine this instrument with a modified overhead projector, the ZoOHPraxiscope, to produce cinematographic visuals based on the principle of the Phenakistiscope. The set starts with two motors that are placed on the OHP, each motor carries a an acrylic rectangle, the rectangles are spinning. The two rotating shapes are projected as translucent shadow objects onto the wall. A vertical line is pushed towards the rotating shapes, on contact, the shapes reverse direction till the other side hits the line again. A beat is created through the interaction of the shapes with the vertical line. A third motor carrying a disc with engraved shapes is mounted, the motor starts to spin, in synchrony with the oscillating shapes, every eighth beat, the motor makes a rotation, the engraved shapes start to spin. Adding more more motor events, the disc goes faster and faster, the shapes smear out can’t be resolved by the eye anymore. Then flicker is tuned in, first at high frequency, barely perceivable softly going down. With the introduction of flicker, the shapes become visible again but now they are dancing, rotating back and forth.
This constitutes the first part of the set, as sound only the motor sounds and a piezo-pickup are used as raw material and then filtered with a band-pass filter. In the second part of the set the contrast is reversed, instead of using translucent shapes and discs, cardboard rectangles that cast dark shadows and picture discs with cut-out shapes are used. As sound now the motor signals are used to trigger the instrument section of a vintage analog drum-synthesizer. The drum synthesizer, a bent ace-tone rhythm-ace fr 2l, produces very deep bass-drum sounds, the piezo pick-up is now attached to a rubber band bent around the vertical line, which also produces a deeper sound. Towards the end the set evolves into an almost danceable techno-set with hypnotic visuals.