8mm Forum: I'm building a box to lock projectors to 24fps

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Posted by Pete Richards (Member # 2203) on March 08, 2015, 06:51 PM:

G'day Campers,
I've been working on locking my various projectors to 25fps for telecine purposes, but have noticed that since Pedro isn't making motor controllers any more, there is some interest in being able to sync projectors to DVD or CD soundtracks for higher quality audio playback.

The project I am creating could be modified to work at 24fps, would anyone be interested in such a unit if I made a run of them?

It would take a bit of work to set it all up, but I'd be willing to do it if there was demand.

I experimented with different methods, but as there are so many projectors out there, and people don't want to hack them up too much, I came up with the least intrusive method I could think of.

Basically the box would work on any projector that has a manual speed control knob. A sensor is fitted inside the projector to monitor the shutter speed, and the motor speed is adjusted to keep the shutter locked at a precise rate. The box drives a motorised pot, which is mechanically attached to the speed control knob on your projector. If the speed needs to adjust slightly up or down to maintain sync, the pot drives the speed control knob appropriately.

When lock is achieved, an LED is lit, you may need to run a slightly longer leader to let the projector get 'in the zone' when firing it up for the first time, and it would be adviseable to have good belts and the projector running as smoothly as possible, so that only minor adjustments are required.

Anyway, that is the gist of it, if there is any interest, let me know and I will make a prototype for someone to test. Again, it will only work if your projector has a speed control knob (or a dc motor, as you could power it from an external PWM controller that had a speed control knob), and you would need to fit an interrupt sensor inside the projector.

As for costs, I am not sure at this stage, I don't know how much the Pedro boxes were, but this should be considerably cheaper. It would consist of a PIC controller chip, PC board, a handful of components (transistors, capacitors etc.) and the motorised pot.

Cheers
-Peter

Posted by Andrew Woodcock (Member # 3260) on March 08, 2015, 06:58 PM:

If full fitting instructions are given out with your products Pete, you know you can count me in.

I would love to be able to screen optical prints on my Beaulieu, and though not ideal setting up a separate audio system each time i want to screen one of these prints, it would at least offer me a true non damaging solution to this as well as giving me an option for some of the fantastic mute prints out there.

Finally, re recording poor soundtrack prints is a big part of the hobby to me, so again, anything that makes this easier and less time consuming for me on this front, is music to my ears Pete!

For me personally, I would love a replica of the the best Pedro box. It works so well on many levels given the digital frame rate display and that of the projector that you can control etc etc.

The best of the Pedro boxes were not cheap, around 700 euros in total I think if you include the internal projector modifications, but to me, this is the only type of total solution for my personal needs for matching quickly digital sources to film for both recording and playback purposes.

Posted by Pete Richards (Member # 2203) on March 08, 2015, 07:53 PM:

If someone could forward me the manuals for the Pedro boxes, and pictures of the boards, I could probably do something similar, assuming Pedro is no longer interested in the business.

Posted by Andrew Woodcock (Member # 3260) on March 08, 2015, 08:35 PM:

If only Pete [Frown]

Posted by Paul Adsett (Member # 25) on March 08, 2015, 10:45 PM:

Does Pedro have patents on his electronic box, and if so have they expired by now, so that his invention is now in the public domain? If they have, then it would be easy, I would think, to reverse engineer one.

Posted by Jason Gronn (Member # 3921) on March 09, 2015, 02:12 AM:

You can count me in Pete if you move forward with this project.

Posted by Steven J Kirk (Member # 1135) on March 09, 2015, 04:43 AM:

I am also interested in this 'syncing lark' and would love to see new devices come to life.

Posted by Andrew Woodcock (Member # 3260) on March 09, 2015, 05:44 AM:

Also Pete, bear in mind that if you can make something of a replica of Pedro's fantastic sync box, then you would need various different electronic boards to control each machines D.C. motor.

These control boards did vary somewhat from model to model but I suppose even creating two for Bauer Studio models and the Beaulieu 708 would suffice for nearly all members to begin with as the Braun Visacoustic 2000 and Elmo GS1200 can directly connect to the Pedro box without any internal board being fitted.

The Goko RM8008 is another machine Pedro catered for but this could surely wait in order of priority.

It's a pity the website isn't still available as it gave quite a detailed explanation which included photographs of the electronics used by Pedro.

In answer to Paul Adsett's earlier query on the Pedro box, though I am totally uncertain, I feel it is unlikely that the Pedro box would ever have been patented for the simple reason it is extremely costly to do so, large numbers of these were never sold and Pedro made these in his spare time as a hobby so I doubt there would have ever been any mileage in it for him to begin to wonder about patenting his designs.

Posted by Pete Richards (Member # 2203) on March 09, 2015, 03:11 PM:

If anyone has his contact details, I would like to contact him to see if he would mind. I'm not looking at this as a financial proposition really, the numbers would be too low, as long as I covered costs and something for my time, I'd be happy.

Surely someone has the manuals, or a board they could photograph in the meantime?

Posted by Andrew Woodcock (Member # 3260) on March 09, 2015, 03:55 PM:

You're right Pete, someone out there must be able to help. There are a fair few of these about even if not huge numbers.

Posted by Andrew Woodcock (Member # 3260) on March 11, 2015, 07:31 AM:

I know Flavio has one of these boxes, so any chance of some assistance for Pete on this to give the rest of the community an opportunity of owning one of these please?

[ March 11, 2015, 09:17 AM: Message edited by: Andrew Woodcock ]

Posted by Andrew Woodcock (Member # 3260) on March 11, 2015, 07:02 PM:

Any news Pete?

Posted by Pete Richards (Member # 2203) on March 23, 2015, 10:56 PM:

I have successfully modified the T610 to take an input from a video source to control the speed.
So, if you feed it a 25fps PAL video input, the projector syncs at 25fps. If you feed it a 24fps video signal, it syncs at 24fps and so on.

I also have a more simple separate board that can just lock the projector to a particular preset fps.

Along the way, I fitted a manual speed control pot to the T610, which is required for the more simple solution, and is just generally handy anyway.

I am working on taking different types of sync inputs, such as a sound-waveform to do pilotone style syncing.

Once I get all that working, I will take a look at other projectors.

Posted by Andrew Woodcock (Member # 3260) on March 24, 2015, 12:49 AM:

The first concept sounds excellent for our needs Pete! I look forward to seeing the outcome and resulting circuit board ,modication instructions and control box etc.

Hopefully this concept can be developed into a user friendly device like the one photographed above and also be extended to other models some time in the future.

Posted by David Ollerearnshaw (Member # 3296) on March 24, 2015, 03:17 AM:

For Pedro old website you could try Archive

I Found This You do need the web address to search.

Posted by Pete Richards (Member # 2203) on March 24, 2015, 03:42 AM:

Andrew, what signal would you want to feed to the projector as it's 'sync pulse?'.

Thanks David, unfortunately the images I need haven't been stored.
http://web.archive.org/web/20090826134650/http://www.super8sync.com/English/B1008S.html

What I really need are the installation instructions that would have been on the CD.

Posted by Andrew Woodcock (Member # 3260) on March 24, 2015, 05:26 PM:

You really do need to make contact with an owner Pete. Hopefully one or two who are out there will repond to your plea.

If not, I'm afraid you would have to design each from grass roots using the projector service manuals etc etc.

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