Projector question
Moderator: Andreas Wideroe
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Projector question
Does anyone know of a Std/Super 8mm projector that has a variable speed motor that gives out a 1 fps sync signal.
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David M. Leugers
- Posts: 1632
- Joined: Thu May 02, 2002 12:42 am
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1 fps pulse projector for R-8mm and S-8mm
My Eumig 710D 
. Seriously, modifying a dual 8mm projector (I personally like the Eumig line) is not too difficult. Installing a reed switch is the usual route. The reed switch is controlled by a magnet installed on the shutter blade assembly so that each time the magnet goes by (the shutter rotates one revolution per frame of film) the reed switch closes and opens back up to give you the one pulse per frame. You'll have to manufacture a bracket to mount the reed switch to line up with the magnet and run the wiring out of the projector or to a projector mounted connector. If you are planning to build your own workprinter, you probably will need to mount a microswitch instead of a reed switch. There are timing considerations etc depending on your application. If you want a projector to sync up with sound for instance and a reed switch will do, I can sell you a brand new switch and magnet from my stock, or modify your projector, or sell you a pristine Eumig dual 8mm silent projector modified with the reed switch. Good luck and keep filming!
. Seriously, modifying a dual 8mm projector (I personally like the Eumig line) is not too difficult. Installing a reed switch is the usual route. The reed switch is controlled by a magnet installed on the shutter blade assembly so that each time the magnet goes by (the shutter rotates one revolution per frame of film) the reed switch closes and opens back up to give you the one pulse per frame. You'll have to manufacture a bracket to mount the reed switch to line up with the magnet and run the wiring out of the projector or to a projector mounted connector. If you are planning to build your own workprinter, you probably will need to mount a microswitch instead of a reed switch. There are timing considerations etc depending on your application. If you want a projector to sync up with sound for instance and a reed switch will do, I can sell you a brand new switch and magnet from my stock, or modify your projector, or sell you a pristine Eumig dual 8mm silent projector modified with the reed switch. Good luck and keep filming!-
David M. Leugers
- Posts: 1632
- Joined: Thu May 02, 2002 12:42 am
- Contact:
Oops
I forgot the variable speed part of the equation! The Eumig I can build for you has several different speeds, but if you need a continuously variable speed projector that is a different story. A projector with a variable speed that can be controlled by an external pulse is a whole different ballgame if that is your goal. I'm doing some research into the externally controlled motor drive because I think that may be the wave of the future for sound projection of film. IMHO 
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shoot1st
Best you choose the sytem depending on the mechanical construction/conditions in the projector and what you wanna do with the output impulses.
The most traditional way is a reed contact + magnet, but an open beam opto interrupter would do the very same job. If possible, you even could choose an opto interruptor with a relatively wide gap (>5mm opening) and mount it in a way, that the shutter passes thru the gap which each turn. The output signal only must be divided thru 3, using a 74LS92 divider for EUR -.50
That´s the way I am syncing motor viewers and tape recorders with perfo tape.
Controlling the projector´s motor is a rather hard job, requiring a good piece of development work. Should be at least a DC motor with electonic speed control. Then you can find yout, where is the resistor that is resposable for the pitch, mostly a potentiometer. Now you can built an interface which contains this resistor several times with every time a diferent speed setting, each resistor controlled by an opto coupler.
A special digital synchronizer unit now has to count the pulses from the reed contact and the pulses from the sound source, compare both, and control one of the pitch resistors depending on the result. It there are more pulses given from the projector than from the sound, the projetor is running too fast and the synchronizer has to select a pitch resistor with a lower speed setting... The way how the resistors are adjusted determines the regulation characteristic. I am using 5 resistors. One for nominal setting, two for "a little bit to slow/to fast" and two for "much too slow/too fast".
Pedro
The most traditional way is a reed contact + magnet, but an open beam opto interrupter would do the very same job. If possible, you even could choose an opto interruptor with a relatively wide gap (>5mm opening) and mount it in a way, that the shutter passes thru the gap which each turn. The output signal only must be divided thru 3, using a 74LS92 divider for EUR -.50
That´s the way I am syncing motor viewers and tape recorders with perfo tape.
Controlling the projector´s motor is a rather hard job, requiring a good piece of development work. Should be at least a DC motor with electonic speed control. Then you can find yout, where is the resistor that is resposable for the pitch, mostly a potentiometer. Now you can built an interface which contains this resistor several times with every time a diferent speed setting, each resistor controlled by an opto coupler.
A special digital synchronizer unit now has to count the pulses from the reed contact and the pulses from the sound source, compare both, and control one of the pitch resistors depending on the result. It there are more pulses given from the projector than from the sound, the projetor is running too fast and the synchronizer has to select a pitch resistor with a lower speed setting... The way how the resistors are adjusted determines the regulation characteristic. I am using 5 resistors. One for nominal setting, two for "a little bit to slow/to fast" and two for "much too slow/too fast".
Pedro