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bruce2bowser@gmail.com: Jun 18 01:55AM -0700 > > > networks.   > > That reminds me. I heard a couple of people talking about about making a paper cube and covering it with aluminum foil and putting it near the router. I never tried it, though.   > Hmmm, maybe some sort of reflector would help the reception upstairs...   Or, I've also heard that putting an empty paper-towel or toilet-tissue roll covered inside and out with aluminum foil there can help, too.

Mike S <mscir@yahoo.com>: Jun 18 02:30AM -0700 >>> That reminds me. I heard a couple of people talking about about making a paper cube and covering it with aluminum foil and putting it near the router. I never tried it, though.   >> Hmmm, maybe some sort of reflector would help the reception upstairs...   > Or, I've also heard that putting an empty paper-towel or toilet-tissue roll covered inside and out with aluminum foil there can help, too.   Ever heard of the 'cantenna'? https://en.wikipedia.org/wiki/Cantenna https://jacobsalmela.com/2013/09/07/wi-fi-cantenna-2-4ghz-how-to-make-a-long-range-wi-fi-antenna/

Jeff Liebermann <jeffl@cruzio.com>: Jun 18 08:34AM -0700 >Ever heard of the 'cantenna'? >https://en.wikipedia.org/wiki/Cantenna >https://jacobsalmela.com/2013/09/07/wi-fi-cantenna-2-4ghz-how-to-make-a-long-range-wi-fi-antenna/   Or, a wi-fi reflector: <https://www.google.com/search?q=wifi+reflector&tbm=isch> There are also wok, salad bowl, colander, DBS dish, etc reflectors.   My salad bowl reflector for USB wi-fi dongles: <http://802.11junk.com/jeffl/antennas/Salad-Dish/> It's not quite parabolic, but close enough to be usable.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

N_Cook <diverse@tcp.co.uk>: Jun 18 01:46PM +0100 Anyone been here? No problem getting inside the intended projector. I tried a lash-up with a salvaged compound lens from a scrap projector and a concave lens from some opera glasses, just holding the lenes in line and a torch, it all seemed to work enough to proceed further.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jun 18 09:57AM -0400 On 06/18/18 08:46, N_Cook wrote: > I tried a lash-up with a salvaged compound lens from a scrap projector > and a concave lens from some opera glasses, just holding the lenes in > line and a torch, it all seemed to work enough to proceed further.   If you put two thin lenses right next to each other, the powers add.   Power in dioptres = 1/focal length in metres, so if you have lenses with focal lengths f1 and f2, the resulting focal length is   f = f1*f2/(f1 + f2)   just like resistors in parallel. So you can make the focal length longer by adding a negative (concave) lens.   Unfortunately you can't change the LCD-to-lens spacing much, so the field angle is more or less fixed. The magnification is thus approximately proportional to the ratio of the image distance to the lens-to-LCD distance. It's a matter of similar triangles--a useful fact from high school optics is that a ray that passes through the centre of a lens is undeviated, so you can easily draw the triangles yourself.   You might be able to get a 1.5:1 improvement or something like that by focusing the projector to its closest setting and picking the right negative lens. That moves the lens further from the LCD, reducing the field angle.   Cheers   Phil Hobbs   -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510   http://electrooptical.net http://hobbs-eo.com

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jun 18 10:07AM -0400 On 06/18/18 09:57, Phil Hobbs wrote: > focusing the projector to its closest setting and picking the right > negative lens.  That moves the lens further from the LCD, reducing the > field angle.   That's the case for an intact projector.   Of course if you can make the lens-to-LCD distance larger, you can make the image smaller. Unfortunately it also gets dimmer quadratically as you do that, because most of the light misses the lens. You can fix that by using a lower-NA (numerical aperture) condenser to illuminate the LCD, but then your system starts getting pretty large.   Also at lower NA you don't need nearly such a good lens, so a simple positive lens or achromat would probably work about better than the combination--by applying some large power and then undoing it again, you get the aberrations of two highish-power lenses, whereas with one lens, you get the lower aberrations of the weaker lens. (There are subtleties here, depending on the detailed design of both the projector lens and the negative lens--some of the aberrations will cancel rather than adding, but the net effect will probably be significantly worse.)   Cheers   Phil Hobbs     -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510   http://electrooptical.net http://hobbs-eo.com

Bill Gill <billnews2@cox.net>: Jun 18 08:11AM -0500 On 6/17/2018 9:43 AM, Michael Black wrote: > time, and then the strap broke, so I abandoned it, rather than buy a > second battery so soon on top of needing a new strap.   >   Michael   I have had 2 of the Casios. Both of them failed when the case broke. They still ran fine, but with a broken case they got filled with moisture and the crystal fogged over.   Bill

"pfjw@aol.com" <peterwieck33@gmail.com>: Jun 18 03:57AM -0700 > Better to feed in the values used in circuit plus a suitable margin. Many times I used beefier trannies than required because they were cheaper. TIPs in particular.   > NT   Ya think? Yeah, I try to reduce the issue of future failures by using replacement parts that are stronger/better than OEM. Except in the case of some resistors and diodes that seem to have a fuse function.   Peter Wieck Melrose Park, PA

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