[OT] Video: The Mechanics of the Film Projector

[zapta]

Not electronics but is interesting nevertheless. This well made video explains how electro mechanical/optical film projectors worked. They even had a X3 frame rate multiplier to reduce the flicker.  If the length of the film between the lens and the audio sensor was too short or too long (vs the nominal 26 frames), you could notice time difference between the audio and the image.

http://youtu.be/En__V0oEJsU

[Mechanical Menace]

Not electronics but is interesting nevertheless.

It still surprises me what we used to do without electronics or computers. If you didn't already know how it works could you recreate it without? I honestly don't think I could. I definitely wouldn't of thought of optically encoding analogue audio. I'd reduce the lifetime with a magnetic strip. Or using a rotating shutter. I'd be trying to control the light source instead.

[Halcyon]

Not just analog audio but even today digital audio is optically encoded onto film. It's fascinating stuff.

This image is 35mm film encoded with SDDS, Dolby Digital, Analog Audio and DTS Time Code. The white spaces are actually the sprocket holes so it gives you an idea how small it is.

[helius]

This barely scratches the surface: no mention of the Geneva Mechanism, and nothing about optics.
There also were shutter wheels that could switch their teeth dynamically based on playback speed.