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How does crystal sync work?


Heersbeer

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Hi,

 

I have been trying to find info on how crystal sync works but I can't find anything. I have a beaulieu 5008s multispeed and I want to sync it. I know a lot about electronics but I need to know how what kind of signal the camera needs to be synced, then, I would be able to make such a control unit because the electronis are not difficult to make.

 

Heersbeer

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Crystal sync involves electronically controlling the speed of the camera to a precise speed.Usually 24 fps in NA or 25 fps in Europe.Of course you can also crystal sync a film camera for 23.97 fps or 29.97 for television work.

The sound recorder is equipped with a crystal to put out a 60hz tone (50hz for Europe) to act as a sync refference.If I am to understand correctly,if you use a mini disc recorder,no modifications to the MD are required if your camera is crystal synced.

Marty

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The process is to send electricity through a piece of crystal which causes it to vibrate at an incredibly high rate, say 10,000 times per second. This vibration can be divided down to a pulse rate for running a motor govenor and because the rate is so high any slight variation due to voltage flux is essentially meaningless (ie, if the vibration rate is actually 10,142 or 9,846 then it won't make any diffence once it's divided down to 24 frames per second).

 

The first time this was done was by rigging a cheap crystal wristwatch to a camera govenor in the 1960s, as the mechanism for keeping that device accurate is the same. This could be you model for how to do this inexpensively yourself. Check out Clive Tobin's website, Tobin Cinema Systems for more information.

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Crystal sync involves electronically controlling the speed of the camera to a precise speed.Usually 24 fps in NA or 25 fps in Europe.Of course you can also crystal sync a film camera for 23.97 fps or 29.97 for television work.

The sound recorder is equipped with a crystal to put out a 60hz tone (50hz for Europe) to act as a sync refference.If I am to understand correctly,if you use a mini disc recorder,no modifications to the MD are required if your camera is crystal synced.

Marty

Most digital electronics get their clock frequency from a crystal. Most such crystals should be accurate enough for sync on a one take at a time basis. That only requires being give or take a frame on a run of a few minutes. The best pro gear has crystals that often keep two time code generators in sync for as much as half a day -- you jam sync in the morning and after lunch. But we still do sticks because they can drift enough to be a problem.

 

 

 

-- J.S.

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Thanks for the info.

I know how to make a crystal sync unit and let it oscillate at any speed I want but now I need to know how to connect it to the camera. On pictures I've seen crystal units using the flash contact but I can't imagaine that's the only connection to the camera. There must be a way to control the speed of the camera without having to increase the voltage of the motor directly(that wouldn't be a problem.

 

Heersbeer

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Thanks for the info.

I know how to make a crystal sync unit and let it oscillate at any speed I want but now I need to know how to connect it to the camera. On pictures I've seen crystal units using the flash contact but I can't imagaine that's the only connection to the camera. There must be a way to control the speed of the camera without having to increase the voltage of the motor directly(that wouldn't be a problem.

 

Heersbeer

Crystal sync is basically a phase locked loop. It compares a tachometer signal from the camera with the crystal, and duty cycle modulates the power to the motor to keep them matched. IIRC, there's a CMOS IC called 4066 that does the bulk of the work. But it's been a very long time since I tried building a crystal motor.

 

 

 

-- J.S.

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Thanks for all the great info but my question remains unanswered. The thing I need to know is what KIND of output signal I have to create(50Hz of 1000Hz pulses) and WHERE to connect it to. I have a function generator that can do anything I want but I don't know how to connect it. I recently bought a nizo camera and from what I understand the nizo camera's are easier to connect to crystal sync so if anybody can help me on that......?

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