8mm Forum: Eumig 810D W/ Sync Mod (More Pics)

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Topic: Eumig 810D W/ Sync Mod (More Pics)

Zechariah Sporre
Jedi Master Film Handler

Posts: 557
From: Ladysmith, WI U.S.A.
Registered: Dec 2010

posted March 01, 2014 08:03 PM

I recently got a Eumig 810D that has a sync modification. I was curious if anybody has ever seen this done on a 800 series projector before. I was wondering if anybody knows how this works? On the handle it says "sync mod 08/20/81". It appears that the power plug is missing, however I don't see any remnant of it inside (kind of weird that part would've been taken out).

I did some more digging and it turns out it has a sensor faced at the shutter (that is all painted black except for one blade). I still don't personally understand how it regulates the speed of the motor, but electronics are beyond me).

[ March 06, 2014, 08:16 PM: Message edited by: Zechariah Sporre ]

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Bill Brandenstein
Phenomenal Film Handler

Posts: 1632
From: California
Registered: Aug 2007

posted March 01, 2014 10:32 PM

Given the disc-drive system these use, I'm at a loss as to how exactly that would work, unless there's some sort of a servo system or pulse generated each time a frame is pulled...

Keep digging. That looks interesting.

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Lee Mannering
Film God

Posts: 3216
From: The Projection Box
Registered: Nov 2006

posted March 03, 2014 02:25 AM

In the good old days we used to glue a magnet on the drive shaft and then fix a reed switch next to it. My money is on this or certainly have a look round for them as they can be fitted in other places. [Cool]

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted March 03, 2014 03:09 AM

Lee is referring to the Craven Synchrodek mod, which synched the projector to a reel-to-reel tape using an external interface device. It compared the pulses (one per frame) from the projector reed switch with pulses from a perforated tape, and controlled the motor speed via a thyristor circuit to keep them in step.
I use a similar circuit to control my 810D at 16.667fps for transfer.
From the writing on your unit, it appears to be a similar idea...
"opto pulse generator"?????

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Ongoing interest in Telecine....

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Lee Mannering
Film God

Posts: 3216
From: The Projection Box
Registered: Nov 2006

posted March 03, 2014 03:34 AM

We used the Cresta unit with this idea as well back in the day. [Cool]

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted March 03, 2014 11:43 AM

Yes, but getting back to Bill's point about the mechanical disc speed control drive, how could the speed of the projector be changed electronically?

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted March 03, 2014 01:42 PM

Paul, Did you read my post? The motor on an 810D CAN be speed controlled over a small range electronically.... as I have said MANY times on this and other Forums.
YES,it CAN!
I set mine to about 18 fps MECHANICALLY using the speed knob and then control it electronically from that speed down to about 15 fps.OR, I can set it MECHANICALLY to about 20 fps and control it down to about 17 fps the same way.
I do it manually with a potentiometer, but it can be incorporated in a servo loop... all you would then need is a stable "reference".

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Ongoing interest in Telecine....

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Bill Brandenstein
Phenomenal Film Handler

Posts: 1632
From: California
Registered: Aug 2007

posted March 03, 2014 09:31 PM

OK, that is really cool. But what's inside the projector that allows you to make the electronic adjustment? Thanks for the details, Martin!

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted March 04, 2014 03:30 AM

I actually use this: http://www.quasarelectronics.co.uk/Item/cebek-r-8-230v-ac-motor-speed-controll er-module-375-watt

but there are many options. Some simple "lamp dimmers" based on thyristors work well, others not so well. This one gives very smooth control and a stable setting if the machine is in good condition.
It is simply wired into the motor leads. I have also incorporated a on/off/on toggle switch to give me Uncontrolled/Motor Off/Manual Control. The normal mechanical Function Knob and Speed Knob work as usual.
I use mine for transfers at 16.67 fps, with a Digital speed readout to make manual control easier.

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Ongoing interest in Telecine....

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Bill Brandenstein
Phenomenal Film Handler

Posts: 1632
From: California
Registered: Aug 2007

posted March 04, 2014 11:40 AM

Nicely done, Martin. Thanks for sharing your engineering with us.

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Zechariah Sporre
Jedi Master Film Handler

Posts: 557
From: Ladysmith, WI U.S.A.
Registered: Dec 2010

posted March 06, 2014 07:05 AM

I will do a little more digging into it. At a quick look I had noticed some wires that went up sort of behind the shutter, like across the body from where the lamp is. It was all covered with duck tape. The one other thing I noticed is they had painted all the shutter except one blade. Then two other wires ran down to the circuit board.

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