CD player and a crystal sync projector

[Konton]

Hey all. I was curious how easy it would be to crystal sync a projector and add a modification where the projector would control the pause function on a CD player.

Assuming the resolving software works and with it we can synchronize and audio with the film, it would be nice to project it with digital audio.

I understand that most projectors reference the oscillation of the AC power for this purpose. Can you just change that reference to a 24Hz oscillator? Or is there a lot more to this?

Once of the things that's great about Pedro's P1008 Synchronizer is that using 1Khz pulses, the projector changes it's speed like a wave in reference to the pulses. You add a 24Hz oscillator and the projector changes it's speed to make the oscillator. It's pretty exact. That's about the way the old Super8Sound Fullcoat Recorder worked.

Now I think accuracy is important which is why I highly recommend Pedro's synchronizer. I suppose with a variable speed projector you could use a tobin speed checker to get it running at close to 24fps. That's about how the II, III, and IV versions of the Super8Sound Fullcoat Recorder worked. But I don't like that. Not accurate enough.

Well let me know what you all think. It would be nice if we could do this and never have to worry about sound striping again.

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Konton the Grey

[#Pedro]

Converting a AC synchronous motor - projector to crystal sync is extremly awful: you need to create a POWER sinus wave out of the crystal generator to drive the motor, which consumes about 100 W. Or you need to built a closed regulation loop, shifting the frequency of the power source for the motor according to the actual speed difference when compared to a crystal oscillator. Not talking about the disortions and influences on the sound amp that way. Better forget that - much cheaper buying a DC projector and converting it in the normal way.

Only connecting one pitch control potentiometer to each of the 5 digital outputs of my synchronizer and connecting that instead of the original pitch control, any regulated DC motor will follow the synchronizer, no matter if tape pulses or crystal. Only an add reed contact for the reference of the actual running speed is required, and a technical "straight and clean" regulation loop is established! Nothing "close to", it?s frame accurate.

The crystal generator for the synchronizer is accurate enough to sync an average film without drifing. I recorded the German video soundtrack of "Dschungle Book" to a S8 print, divided in two 800 ft reels. No problem at all, after finding the start frame, to sync one complete roll in one run.

To remote control a cd player, the easyest way would be a relay in parallel to the motor.

Better would be, to record a standard 1000 Hz / 0 dB signal 10 seconds before the first frame onto the sound stripe of the leader. A simple circuit connected to the speaker or line output would detect this beep as first sound event and start the cd player.
Then you now, that you must include a 10 second sync leader in your soundtrack design and put a flash frame to that position in the leader. To show the film, you only set the CD in pause position, load the film and start it. When the sync beep starts, the CD will follow and after 10 seconds the show can begin... without searching for any start frame.
In Germany a small electronic company developed such a box, with inbuilt crystal oscillator, ready to connect to the Elmo GS1200 projector (ONLY this model).

Pedro

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