tornitore45 wrote:You are planning on a "touch" "notouch" detections, I suppose. Lamp ON; Lamp OFF within a1/1000 or so.
Yes, I do, and if I live long enough, I'd like to cobble one together.
I think an analog ohmmeter would be the best choice. It would give a better indication of an equal touch, and already has a low draw which wouldn't do much arcing dammage to the contact surfaces. Someone with more electronic ability could probably work out a capacitor circuit like in older automotive point ignition system to reduce arcing even more.
Some sort of brushes contacting the thimble or rod would give a more consistant reading than through the oiled threads. A longish, thin, flexible, stranded, uninsulated wire run through a straight insulating tube able to be clipped to the thimble when close to touching would probably do better.
Also, a 4' pendulum would probably far exceed the acaccuracy of the mike and electrical contact consistancy. Adding in slight temp changes, and achievable flatness of the base it could drive a sane perfectionist (if there is such a thing) over the edge.
If the unit is turned 180° on a close to level surface, the two readings could be averaged to make it actually a level.
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Years ago after a lot of discussion of precision levels on this board, I decided to build a quick level using a pendulum. It was crude and not meant to be useful.
Best viewed 'Original Size'. (Click the magnifying glass twice in the lower right corner.)
http://smg.photobucket.com/user/skytop1 ... ort=3&o=13
(Clicking "Previous" will show the spherical mount under the tail end of the old Sheldon bed mentioned in my previous post.)
The base of the level was 24" long. The frame was 3/16" rod and coat hanger oxy/acetalene welded.
The two levers multiplied the difference between having the .005" feeler guage under one end and not as seen in the insets. The camera was mounted on a tripod. I was satisfied with the results, and the fabricated parts hang on the wall of the shop sparking questions less than once in a blue moon.
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Another point made more than once by my father:
He kept his BP leveled. It was handy to be able use a level in some setups.