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Screen Masking Idea.pdf 15.1396484375k . file
Regarding reed switches; someone back on ScottJ007's thread mentioned that there may be a gap in where the mask would stop -- depends from which direction the mask is coming from. From the left it will stop X amount away from the reed switch & coming from the right the mask will trigger the reed swt in a different spot. The mag's field is wider than the mag itself, so the field will trip the swt in a diff place depending on the direction of approach. The width may not be large enough to matter maybe?
I had thought about placing movable (for adjustable AR pre-sets) slotted opto sensors along a track (wood working miter track?). A small tab mounted on the mask edge top would trip the swt as it passes thru the slot, of course alignment would be critical (slots are are only only a few mm wide). Moving the opto along the track would position pre-set points. Wiring less of a problem this way, no worries about sensor wiring on a moving mask. See link below for two premounted slotted opto sensors; OSU-69 & OSU-40.
Another possible sensor: Hall Effect sensor also could be mounted along an adjustable track (again maybe a mitre track). Electroncally I wonder how you could tell the MP which sensor was which pre-set? No idea...
On the motorized curtain track I mentioned in an earlier post; I wondered about using a tracked sensor setup & some how using them to give a "stop command" at each point when tripped. The system has a STOP button on the rmt ctl & wall swt, would sorta dulication the swt press. But I guess the system would be hampered by stopping at each preset coming from either direction. Just a thought.
Here's a animation I found on this forum, shows a dual roll down mask. This approach yields two possible ARs, good idea if you have no room on either side for curtain stack back, but only need two ARs.
If one could mount a motorized curtain track behind the top assembly, a connection between the L & R master carriers could pull the two rollers in & out along the shaft. Another connecting rod between the rollers to the curtains pulls them along as well.
Here is a very basic drawing (from the British Film Club) using a top mounted single motorized roller that moves two masks towards & away from each other. The cables are wound in opposite directions around the top roller, as one lowers, the other is pulled up equally. Of course the image would have to be centered between the masks for this to work... Have seen several versions of this done on this forum.
Motor Control Circuit.pdf 12.017578125k . file
Non-encoder Based Motor Controller.pdf 173.3994140625k . file