- SMD capacitors - 2 Updates
- Cutting Plexiglass (Perspex) - 6 Updates
- Shameless Plug for Kutztown XXXVII - 1 Update
| Ralph Mowery <rmowery28146@earthlink.net>: Aug 31 10:27AM -0400 In article <oo85si$sgh$1@dont-email.me>, gnuarm@gmail.com says... > I think you just answered your question. If the caps have polarity markings > they are polarized. If they don't have polarity markings, how do you know > you have any installed correctly? Someone sent a pix with several kinds of the SMD capacitors. A couple of them had a pointed tit on one end. I did not know that,so would have missed that as a polariaty mark. If I had just looked at the capacitor, I probably would have dismissed it as just a blob of material instead of a polarity mark. Sometimes it helps to know all the small details of the components. I don't know, but guess that some could not have any marking and it could depend on how they are placed in the reel they come in. |
| rickman <gnuarm@gmail.com>: Aug 31 11:54AM -0400 Ralph Mowery wrote on 8/31/2017 10:27 AM: > missed that as a polariaty mark. If I had just looked at the capacitor, > I probably would have dismissed it as just a blob of material instead of > a polarity mark. I don't know if that *is* a polarity mark. I'm not sure what you are describing, but I don't recall seeing any SMD polarized capacitors that don't have *clear* markings of polarity. Do you have an image or can you find a similar cap on the Internet? > Sometimes it helps to know all the small details of the components. I > don't know, but guess that some could not have any marking and it could > depend on how they are placed in the reel they come in. I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity. -- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998 |
| Stephen Wolstenholme <steve@easynn.com>: Aug 31 01:00PM +0100 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote: >Any suggestions as to a good, safe approach to cutting the plastic? Repeatedly score it with a suitable blade and snap it along a hard strait edge. When I was using a lot of perspex I had a strait edge made with a steel rule glued to a wooden board. Occasionally I needed to use two boards clamped in a vice. Steve -- http://www.npsnn.com |
| Chris Jones <lugnut808@spam.yahoo.com>: Aug 31 10:24PM +1000 On 31/08/2017 08:57, Dave M wrote: > bit dangerous due to the small size of the work. Clamping would be tricky. > Any suggestions as to a good, safe approach to cutting the plastic? > Dave M As others have said, use a CO2 laser. About 40 watts or higher should do the job. They cost from about $4000 upwards, and are so useful that many hobbyists and clubs have them. It leaves a nice smooth edge on acrylic. Acrylic is one of the materials that it can cut well and safely. (e.g. Don't ask them to cut PVC, it makes acidic fumes that attack the mechanism of the machine and poison the bystanders.) |
| gray_wolf <g_wolf@nospam.com>: Aug 31 07:35AM -0500 On 8/30/2017 5:57 PM, Dave M wrote: > I've thought about using a table saw with a cabinet-grade finishing blade. > That's possible, but somewhat dangerous due to the small size of the > filters. A triple chip for plastic would be your best bet. |
| Joseph Gwinn <joegwinn@comcast.net>: Aug 31 09:43AM -0400 On Aug 31, 2017, oldschool@tubes.com wrote > it's still hot and soft, but that did work in the end. (The soldering > iron tip was pretty much trash though, I ssaved it for future plexiglass > holes, but would never try to solder with it). When drilling plastics like plexiglass, one does it flooded with tap water, to prevent overheating amd melting into a gooey mess. Do not use oil - this will crack most plastics. Joe Gwinn |
| Neon John <no@never.com>: Aug 31 10:03AM -0400 On Wed, 30 Aug 2017 17:57:06 -0500, "Dave M" <dgminala@mediacombb.net> wrote: >Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas >(Perspex) for LED displays? Use the score-and-snap method. Purchase a scoring tool from any of the big box stores or many hardware stores. This tool has a backward pointing scoring point and cuts a 90 deg Vee. Score the plastic along a straightedge to about 1/3 the thickness. That's about 3 passes with the scoring tool. Position the plastic on a counter or bench with a sharp edge, locate the score over the edge. Place your palm on the plastic and firmly push down. The acrylic will cleanly snap. If you get a ragged break or a chunk of plastic remains on one end, you didn't score deeply enough. John John DeArmond http://www.neon-john.com http://www.tnduction.com Tellico Plains, Occupied TN See website for email address |
| "Dave M" <dgminala@mediacombb.net>: Aug 31 09:44AM -0500 Jasen Betts wrote: > send these guys 1:1 scale SVG with your outlines, they'll cut them > into a sheet. > they seem to have a "first order free" deal going at the moment. This looks promising. I'll look into it and see what the costs are (future projects). It's a great concept, sorta like sending Gerber files to a PCB house, and they make the board to my specs. OK, thanks for all the suggestions. I just got a response from an Ebay seller, saying that if I buy a suitable panel of his Plexiglas, he will cut into pieces of my specifications at no charge!! Can't beat a deal like that. BTW, the seller's Ebay name is seefinestore, based in New York. Don't know if he gave me a one-time deal, or if he will do this for any order, but it solves my immediate problem. Thanks for the pointer to ponoko, I'll keep it for reference for future projects. Dave M |
| "pfjw@aol.com" <pfjw@aol.com>: Aug 31 06:40AM -0700 http://www.dvhrc.com/kutztown.html Can't believe this has been going on since 1992, and getting bigger with each event. September 15/16, with dealer set-up on the 14th. As usual, I will be at the club table for the clinic, and running Radio Free Kutztown. Camping is free, admission is free. Probably 200+ dealers in 35,000 s.f. under roof and about 1/3 again as much in the open. Look at the pictures. Peter Wieck Melrose Park, PA |
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