Turn table animation machine

I built this animation machine in collaboration with Jisho Roche Adachi  for  an Exploratorium event focused on time. Jisho an Illustrator / Painter and an old friend who happens to share an interest in animation machines. You can see more of Jisho's work here .  Though originally we wanted to explore using a prism shutter similar to high speed cameras, we tried using a rotating cube and later hexagonal prism which I milled out of an acrylic rod.

Shutters were supposed to spin with a wheel on the turntable (as seen in Jisho's notebook below). These prism wheels proved very hard to synch up and were abandoned after the first few days. 

 The physical design of this project ended up drawing directly from the Electrotachyscopes which I built as a student at Oberlin and the later point source projector project . The machine uses an improved electrotchyscope strobe circuit and laser etched mirror disks based off the the point source projector's slides.

The Electrotachyscopes used an optical gate trigger for the strobe which was less than reliable. For this machine I used neodymium magnets in pockets in the record platen and a reed switch in the tone arm.  This design really stays true to the record player's original form and function. The reed switch in the tone arm reads the magnets and tells the strobe to fire only when its placed over the side of the platen.  We started out with a simple ring of 12 magnets around the edge of platen. However, as this was an automatic turntable we were able to take advantage of the 7'' and 12 '' settings to play different strobe rate "tracks" in the platen. In the photo above there is an inner track of 12 flashes per rotation and an outer of 18 flashes per rotation. Due to the position of the strobe circuit, we ended up shortening the tone arm,  but if we had been able to leave it full length we may have been able to use the 10'' setting for  a third strobe track.       

Here is a detail of the strobe circuit with the adjustable Locline light arm and trigger wires running to the magnetic reed switch in the tone arm.  

Here is the machine playing a 12 frame Muybridge animation sequence as seen on the machine's movable velum screen.

Projection detail.

In another adaptation we added a spool to the top of the platen allowing it to play a loop of acetate Jisho had drawn based on video of people walking around the Exploratorium. We discover that this format could either be used to animate the film itself by shining the light through the screen behind it or as a simple shadow projector by placing the moving film between the led light arm and the screen.