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fr:meetings_projects:spectral:mire-wandering:wandering-16mmprojection:start

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16mm Projection Devices

What Do We Want?

Expanded cinema techiques are made more difficult by the design of projectors. We want to:

  • Change motor speed intuitively (including reverse)
  • Change lamp brightness (including automated fades)
  • Make it lighter
  • Add modifiers in front of the lens
  • Preserve optical sound playback if possible

Supported Projectors

We plan to modify these projectors to meet the goals above

Eumig P 26

(available in 8mm and 16mm, so be sure you know which one you are buying)

Pros:

  • Lghtweight and portable
  • Gate is easily accessible, great for quickly changing film loops
  • mechanism is very accessible via 1:1 drive shaft on outside of projector
  • mechanism is very low friction, requiring less motor torque

Cons:

  • Hard to find outside of Austria
  • No sound
  • Doesn't support large reels

Eiki NT and RT

Pros:

  • Very common around the world
  • Supports optical sound

Cons:

  • Big and heavy (but can be reduced by replacing motor and replacing AC power components)

What We Will Build

Motor Unit

Stepper motor (to provide precise speed control regardless of load) controlled by buttons and knobs, coordinated via Arduino micro-controller. 12v power from wall adapter or battery pack.

Lighting Unit

Powerful LED with dimming/fading controlled by buttons and knobs, coordinated via Arduino micro-controller. 12v power from wall adapter or battery pack.

  • Should be interchangeable (as much as possible) between projectors (but P 26 and Eiki will need different mounts/adapters)
  • Klarus G15 flashlight is perfect (Thanks Guillermo): Very little hotspot, 4000LM brightness, ideal throw angle

Components:

LED

  • Cree XHP70.2 (datasheet)
  • Klarus flashlight uses cool white (5000k) but 3500 and 3000 are also available

Reflector

  • Klarus flashlight reflector is perfect: “orange peel” aluminum parabola with approx 20mm dia and 15mm depth
  • Very few small diameter reflectors available for the XHP70.2 LED
  • Big reflector (Amazon)
  • “SMO” reflectors are smooth, “OP” reflectors are orange peel (textured). We think we want OP since it helps diffuse the hotspot

Heatsink and 12v fan

  • 25mm fan and heatsink?

LED driver circuit

  • 12v @ 2A output constant current (LED is 2.4A max)
  • Enable pin that we can ontrol with PWM from Arduino for dimming

Arduino

  • Make sure we have enough pins for 1 pwm out and user interface inputs
  • max PWM frequency (to avoid flicker)
  • onboard USB is nice, but avoid arduino Nano since USB is ruined when you flash with wrong CPU frequency selected

User Interface

  • Pot for brightness
  • on/off button (fades up or down based on position of fade time pot)
  • Pot for Fade Time

12v power supply

  • Motor might draw 2A max
  • LED might draw 2.4A max (depending on LED driver)

Optical Sound Update for Eiki

When we remove the AC circuitry in the Eiki, the amp board goes to. We will design a simple DC powered preamp with volume control to provide a line out from the optical sound reader.

  • Should accecpt 12v and filter it a LOT since the motor controller and stepper will be causing lots of power supply noise

Turret for Lens Accessories

A 3D-printed turret to add colored filters, pinhole discs, or other nonsense in front of the projector lens

  • Should attach to front of projector or directly on lens
fr/meetings_projects/spectral/mire-wandering/wandering-16mmprojection/start.txt · Dernière modification : 2023/03/10 15:22 de pierre