Expanded cinema techniques are made more difficult by the design of traditional 16mm projectors. A total re-design is outside our expertise, so we modified existing projectors in these ways:

• Removed AC transformers and original motor to save weight
• Replaced motor with brushless DC equivalent so we can control film speed intuitively (including reverse) without affecting lamp
• Replaced lamp with dimmable LED
• Removed the projector's shutter. The new LED lamp flashes to emulate the missing shutter blades. This saves power and heat, and allows us to adjust the number of shutter blades, adjust the virtual “shutter angle”, or disable the shutter completely to reveal the pull-down movement
• Added knobs, switches, and buttons for new features
• Added Arduino-compatible ESP32 micro-controller to control the projector (Features can be added in the future by code updates)
• Preserved optical sound playback using LED “exciter lamp” and photodiode pre-amplifier
• Provided future option for hand-cranking and external power (spinning wheel, sewing machine…) In February 2024 we didn't have time to add a hand-crank, but the projector code has been designed with external cranking in mind, so it can be added in the future.

We modified 2 small silent projectors from the 1950's (Eumig P26) and 1 sound projector from the 1970's (Eiki R series). See here for a discussion of why we chose the ones we did.

• Bill of Materials (Parts List with links)
• GitHub Repository (Code, 3D models, datasheets, etc)
• Construction Guide (Step By Step Instructions to build your own)
• Research Journal (Notes about our process, including experiments, successes, failures)
• User Manual

SPECTRAL is co-funded by the Creative Europe program of the European Commission.